Electric submersible pumping unit

ABSTRACT

An electric submersible pump assembly with integral heat exchanger, high-speed self-aligning bearings, and dual bearing thrust chamber is described. The described pump assembly, modules, and components may be used for operating an electric submersible pump at high speeds as well as over a wide range of speeds and flowrates without replacing downhole equipment. The described pump assembly may be shorter than comparable pump assemblies and may be assembled offsite, thereby leading to faster and easier installation with less down time. By operating over a wide range of speeds, the disclosed pump assembly allows the operator to reduce overall inventory, reduce down time for the well, and avoid other complications associated with replacing a pump assembly or other downhole components.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of Ser. No. 16/282,811 filed Feb. 22,2019 and issued as U.S. Pat. No. 10,538,999 which claims priority toU.S. Provisional Application No. 62/634,423 filed Feb. 23, 2018, thedisclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present inventions are directed to electric submersible pumpassemblies for wells and in particular to high-speed components relatedto electric submersible pumps.

BACKGROUND AND SUMMARY OF THE INVENTION

Electric Submersible Pumps (ESP) are widely used in the production offluid from oil and gas wells. Traditional ESPs have a centrifugal pumpcoupled to an electric motor. The motor is typically protected fromwellbore fluid ingress by a seal (also referred to as protector orequalizer). The seal section is located between the motor and the pumpwhich serves to reduce any pressure difference between the wellborefluid exterior of the motor and the lubricant on the interior of themotor.

The rotary pump in many ESPs includes a rotating shaft, impeller, andstationary diffuser. The impellers are coupled to the shaft and createlift as they rotate, driving wellbore fluid up the well. A standardinduction type motor may include a single continuously wound stator, asingle shaft, one or multiple induction type rotors mounted on theshaft, and rotor bearings to the centralize the shaft.

Various disclosed embodiments of the invention may have one or multipleadvantages over standard ESP units. Some disclosed embodiments utilize awider range of operating speeds, utilize an active cooling system toreduce motor temperature rise, reduce the amount of time required toassemble or install a unit, and/or improve the power efficiency of theESP system.

Disclosed embodiments may also reduce the inventory required through theuse of standardized components, reduce capital requirements, reducepersonnel requirements, and/or decrease rig exposure to an open wellbore during installation, thereby increasing safety.

Some of the disclosed embodiments incorporate high-speed downholecomponents including pumps, seals, gas separators, intakes, motorsand/or downhole sensors.

Some embodiments comprise a permanent magnet synchronous motor with acontrol system for speed regulation. Some embodiments may additionallyor alternative comprise a high-speed pump, seal section and/or gasseparator connected and aligned along a common axis. In someembodiments, the motor may be of modular construction and/or have anactive cooling system that increases heat removal from the system vialubricant circulation through a heat exchange module. In certainembodiments, a downhole sensor may be utilized to control the operationof the ESP in substantially real time.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts a schematic of an exemplary embodiment of a disclosedsystem.

FIG. 2 depicts a schematic of an upper portion of an exemplary pump.

FIG. 3 depicts a schematic of a middle portion of an exemplary pump.

FIG. 4 depicts a schematic of a lower portion of an exemplary pump andupper portion of a gas separation module.

FIG. 5 depicts a schematic of a lower portion of an exemplary pump andupper portion of an exemplary gas separation model.

FIG. 6 depicts a schematic of an lower portion of an exemplary gasseparation module and upper portion of a seal section.

FIG. 7 depicts a schematic of a portion of an exemplary seal section.

FIG. 8 depicts a schematic of a portion of an exemplary thrust chamberin the lower portion of the seal section.

FIG. 9 depicts a schematic of a portion of an exemplary thrust chamberand motor head module.

FIG. 10A depicts an exemplary embodiment of a disclosed motor.

FIG. 10B depicts a schematic of a portion of an exemplary motor headmodule.

FIG. 11 depicts a schematic of a portion of an exemplary power module.

FIG. 12 depicts a schematic of portion of an exemplary base module.

FIG. 13 depicts a schematic of a portion of an exemplary central heatexchange module.

FIG. 14 depicts a schematic of a portion of an exemplary lower heatexchange module.

FIG. 15 depicts a schematic of a portion of an exemplary base modulewith lubricant return.

FIGS. 16 A, B, and C, depict schematics of an exemplary central heatexchange module.

FIGS. 17 A, B, and C depict schematics of an exemplary lower heatexchange module.

FIG. 18 depicts an exemplary flangeless connection.

FIG. 19A depicts an exemplary assembled sleeve assembly.

FIGS. 19 B and C depict components of an exemplary sleeve assembly.

FIGS. 20A and B depict embodiments of a bushing with a surface feature.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, certain details are set forth such asspecific quantities, sizes, arrangements, configurations, components,etc., so as to provide a thorough understanding of the presentembodiments disclosed herein. However, it will be evident to those ofordinary skill in the art that the present disclosure may be practicedwithout such specific details. In many cases, details concerning suchconsiderations and the like have been omitted inasmuch as such detailsare not necessary to obtain a complete understanding of the presentdisclosure and are within the skills of persons of ordinary skill in therelevant art.

For the purposes of clarifying the various embodiments of the disclosedinventions, the systems and assemblies described below are presented inthe context of an exemplary electric submersible pump. It will beapparent to those of ordinary skill that the disclosed system may beutilized with other equipment, components, and applications.

Exemplary Electric Submersible Pump Embodiments

In a non-limited exemplary embodiment, the disclosed inventions relateto an electric submersible pump (EPS) assembly. As shown in FIG. 1, theexemplary ESP comprises at least one centrifugal pump module (6), a gasseparator (7), a seal section (8), an electric motor (9) with an activecooling system, and a downhole sensor unit (10). In operation, a motorgenerates torque, which is communicated through a motor shaft into aseal section shaft. The seal section shaft transmits torque up to thegas separator shaft, which transmits torque to the pump module. The pumpmodule utilizes the motor generated torque to lift wellbore fluid up awell bore.

As shown in FIG. 2, a pump module (6) may have a discharge head (14).The discharge head (14) may be integral to the pump module (6) or beattached by any of a variety of suitable techniques as known in the art.The discharge head (14) may be connected via a flange to the pump head(16) using a flange or flangeless connection. In some embodiments, thedischarge head (14) will be connected to the pump head (16) usingcorrosion resistant fasteners (15) such as, for example, screws. A pumpshaft (18) may use a split ring to lock into an axially adjustableassembly (19). The pump shaft (18) may include a keyway including, forexample, dual keyways, that attach the impellers (23) and bearingsleeves (24) to the shaft. In many embodiments, the impellers (23)and/or bearing sleeves (24) are rotationally fixed to the shaft (18). Itwill be understood that the term impeller, as used herein, may refer toany rotating component that is used to move a fluid.

A diffuser or, in some embodiments, a stack of diffusers (22) withbearing bushings, and impellers (23) may be placed inside the pumphousing (17). A compression tube (21), a radial bearing support (20)and/or a pump head (16) may also be secured at least partially withinthe pump housing (17). In some embodiments, the pump head (16) maycontain a high speed, self-aligning radial bearing system. In someembodiments, a high speed, self-aligning radial bearing system may beseparate from the pump head or integral to the pump head.

As shown in FIG. 3, a pump module (6) has at least one radial bearingsupport (25). In preferred embodiments, radial bearing support (25)comprises a radial bearing system comprising a bushing housed in abearing support and a sleeve (25A) mounted on a shaft. In preferredembodiments, the radial bearing system comprises a high-speed,self-aligning (HSSA) bearing.

As shown in FIG. 4, a pump shaft (18) may have splines which connect toa coupling (28). In some embodiment, the splines described here, as wellas throughout the application, may be involute splines, SAE6 splines, orother variations which allow a shaft to connect to a coupling. Thecoupling (28) may transmit torque from the shaft of a gas separatormodule (7) to the pump shaft. The bottom flange (27) of the pump module(7) may be secured to the top flange (30) of a gas separator module (7)using fasteners (29) which may include, for example, high strengthcorrosion resistant screws. In many embodiments, impellers (23) andbearing sleeves (24) form a rigid connection with the pump shaft (18).The bottom flange (27) may contain a radial bearing system, preferablycomprising a HSSA bearing used to provide radial support to the pumpshaft (18). It will be appreciated that the terms bottom flange and basemay be used interchangeably throughout the specification. It will alsobe appreciated that the terms top flange and head may be usedinterchangeably throughout the specification.

As shown in FIG. 5, a gas separator module (7) may comprise a top flange(30) with a HSSA bearing (31) and phase crossover (32). Phase crossover(32) directs the gas phase of the production fluid to the wellboreannulus and the liquid phase into the pump. A spiral inducer (34) may belocked to the gas separator shaft (33) via a keyway or dual keyways. Agas separator housing (103) may be fitted with sleeves (35), to protectthe inner surface of the gas separator housing from abrasive wear andcorrosion. In some embodiments, these sleeves (35) may comprise a metalceramic such as, for example, tungsten carbide, silicon carbide, orzirconium carbide, and/or other materials that provide wear resistance,abrasion resistance, corrosion resistance, or other desirableproperties.

As shown in FIG. 6, the bottom flange (38) of the gas separator module(7) may comprise a HSSA radial bearing and have at least one port forthe inflow of wellbore fluid. Wellbore fluid may refer to single and/ormulti-phase wellbore or formation fluid. In some embodiments, the bottomflange (38) of the gas separator module may be fitted with a screen(104) for removing debris from the wellbore fluid. Torque may betransmitted to the gas separator shaft (33) from the seal section (8)through a splined coupling (105). The bottom flange (38) of the gasseparator (7) may be connected to a flange (41) of the seal section (8)via high strength corrosion resistant screws (39).

The seal section (8) may be a multi-chamber assembly which serves atleast one of four main functions: (1) transmitting torque from the motormodule to the pump module; (2) absorbing thrust from the pump module;(3) protecting an internal chamber of the motor module from wellborefluid; and/or (4) reducing a pressure differential between the interiorand exterior of the motor. It will be appreciated that the terms sealsection, equalizer, and/or protector may be used synonymously within theindustry to refer to a seal section

In some exemplary embodiments, a seal section (8) may have a top flangeor head (41) with a HSSA bearing, a dual key shaft and/or seal sectionshaft (40), and a mechanical seal (42). In some embodiments, the sealsection shaft (40) comprises splines on both ends. In some embodiments,the mechanical seal (42) is a high-speed mechanical seal configured toprotect the seal section (8) from wellbore fluid ingress around theshaft (40). In preferred embodiments, the seal section shaft (40) isfitted with a HSSA bearing sleeve (43), which interact with a HSSAbearing bushing. Top flange (41) of the seal section may have a ventport (106) for removal of air or other gases when the internal chamberof the electric motor is filled with lubricant. In some embodiments, thelubricant serves as a coolant and/or is a dielectric or substantiallydielectric fluid. Top flange (41) may also have a tangential port (107)for removal of sediment, particulate, or other solids, around themechanical seal (42). The body of the top flange may have a port with atube (109) inserted in it which facilitates the transmission of anexternal hydraulic pressure from the wellbore fluid to the filling fluidand/or lubricant of the seal section and/or electric motor. In someembodiments, the tube (109) follows a labyrinth scheme. In someembodiments, the labyrinth transmission of hydrostatic pressure betweenthe external wellbore fluid and internal lubricant may be carried usingtube (109) and tube (110). The seal section head (41) may be connectedto the upper seal section housing (44).

As shown in FIG. 7, the bottom of the upper seal section housing (44)may be connected to the upper seal section body (46) where a secondmechanical seal (45) may be installed. In such embodiments, the secondmechanical seal (45) separates the labyrinth chamber from a bag chamber,additional labyrinth chambers, or combinations thereof. The seal sectionbody may also contain a HSSA bearing, (111), a vent port (112) and/or aconnecting channel (113) between an upper labyrinth chamber and acentral chamber of the bag chamber section and/or additional labyrinthchambers. The specific configuration of labyrinth chamber and/or bagchamber may depend on the conditions of the well, other components ofthe ESP, and/or other factors.

The upper seal section body (46) may be connected to the central sealsection housing (114). The bottom portion of the upper seal section body(46) may be fitted with a tube (115) of the second labyrinth to transmithydrodynamic and/or hydrostatic pressure from the top chamber to thecentral chamber. The central seal section housing (114) may be fittedwith an upper bag support (47) and the bag may be secured with a clamp(116) to the upper bag support (47). In some embodiments, the upper bagsupport (47) may be connected to a lower bag support (118) via a supporttube (117). Support tube (117) facilitates a rigid connection betweenthe upper bag support (47) and lower bag support (118). In someembodiments a single bag may be used. In other embodiments a pluralityof bags may be arranged in succession using a similar mountingtechnique.

As shown in FIG. 8, a lower bag support (118) may be connected to alower seal body (49) between the central seal section housing (114) andthe thrust chamber housing (50). The lower seal section body (49) may befitted with a HSSA bearing (119) and/or a vent port (120). The lowerseal section body (49) may contain a high-speed mechanical seal and aHSSA bearing and may be threaded into the thrust chamber housing (50).In some embodiments, the thrust chamber housing (50) contains single,dual, or multiple thrust bearings (51) and (52).

In some embodiments, each of the thrust bearings (51 and 52) may befitted with a spring damper (121 and 122). The spring dampers mayfacilitate a more even or substantially uniform distribution of theoperational thrust load between the thrust bearings (51 and 52). In someembodiments, the spring dampers may comprise a Belleville washer stack.In some embodiments, the washer stack is run in a parallel configurationto promote even thrust load transfer across the two thrust bearings.

The top thrust runner (51A) may be dual-sided and engage against astatic face (123) to absorb potential up-thrust. Up-thrust may beencountered during start-up. A down-thrust face on the top thrust runner(51A) may engage against the upper thrust bearing assembly (51) ifdown-thrust is encountered. In some embodiments, a single sided runner(52A) may engage against a lower thrust bearing assembly (52) in theevent of down thrust.

A thrust chamber heat exchanger may comprise an inner wall (124). Insome embodiments, the exterior of this inner wall may be spiraled orotherwise comprise a helical or other tortuous pathway used to movemotor oil or other lubricant from the top of the thrust chamber to thebottom of the thrust chamber in close proximity to the thrust chamberhousing 50. The lubricant pathway between the inner wall of the thrustchamber heat exchanger and the thrust chamber housing (50) may behelical or otherwise tortuous path in order to increase the residencetime of the lubricant in the heat exchanger pathway, thereby increasingthe amount of heat dissipated through the thrust chamber housing (50) tothe wellbore fluid. Once the circulated lubricant reaches the bottom ofthe thrust chamber it may passes through a filter (126) before beingcirculated through the thrust chamber again.

In some embodiments, the lubricant has a high dielectric strength and/ora high viscosity. In some embodiments, the lubricant has a dielectric ofgreater than 20 KV, or greater than 25 KV, or greater than 30 KV, orgreater than 35 KV. In some embodiments, the lubricant has a dielectricof at most 20 KV, or at most 25 KV, or at most 30 KV, or at most 35 KV.

In some embodiments, the lubricant has a viscosity at 40° C. of at least60 CST, or at least 70 CST, or at least 80 CST, or at least 100 CST, orat least 120 CST, or at least 140 CST. In some embodiments, thelubricant has a viscosity at 40° C. of at most 70 CST, or at most 80CST, or at most 100 CST, or at most 120 CST, or at most 140 CST, or atmost 160 CST.

In some embodiments, the lubricant has a viscosity at 100° C. of atleast 5 CST, or at least 7 CST, or at least 10 CST, or at least 12 CST,or at least 14 CST, or at least 16 CST. In some embodiments, thelubricant has a viscosity at 100° C. of at most 7 CST, or at most 10CST, or at most 12 CST, or at most 14 CST, or at most 16 CST, or at most18 CST.

As shown in FIG. 9, the lower part of the thrust chamber housing (50)may be designed with a threaded connection. This threaded connection maybe used to connect the thrust chamber housing (50) to the seal sectionbase (56) which may be fitted with a HSSA bearing (127) and/or a reliefvalve (128) for factory filling of the seal section with coolant,lubricant, dielectric fluid, or a fluid with more than one of theseproperties. One or more screens may be located at (500).

The seal section base (56) may be fitted with a screw (129) whichactuates the valve (128) and allows for the flow of the lubricant fluidinto the free cavity between the bottom flange of the seal section andthe top flange of the motor module. Bottom splines on the seal sectionshaft (40) may be mated to a coupling (131), which may be used totransmit torque from the motor head module shaft (59) to the sealsection shaft (40).

As shown in FIG. 10A, in some exemplary embodiments, the motor module(9) may be a permanent magnet synchronous motor of modular construction.The combined motor module (9) may comprise, a head module (310), Powermodules (320), and base module (330).

As shown in FIG. 10B, in some embodiments, the head module (310)comprises a HSSA bearing as well as a head (57), a hollow head moduleshaft (59) which may have splines, a head module housing (134), aterminal block (60), and/or a flangeless connection (64) that may beused to mate the head module to the top of a power module.

The terminal block (60) may hold three terminals that mate to the motorlead cable and seal the connection against the ingress of wellborefluids. These terminals may be connected internally via lead wire (132)to the female terminals in the insulation block (68). The bottom part ofthe head (57) may be fitted with a protective insert (61) which may beused to protect the lead wire from the rotating head module shaft (59)

The head module (310) may also be also fitted with a filling valve (133)which may be used to fill the internal chamber of the electric motorand/or lower chamber of the seal section with lubricant when the unit isrun in combination with a seal section (9).

The head module housing (134) may be threaded on to the head (57) and/ora bearing support (71). In some embodiments, the bearing support isintegral to the head (57). A HSSA Bearing (62) may be installed in thehead module housing and held in place by a retaining nut. In certainembodiments, the bearings support, whether integral to the head or aseparate component, may also comprise mounting holes for any femaleterminals that connect to the male terminals on a power module.

The lower part of the head module housing (134) may have a flangelessconnection (64). In an exemplary flangeless connection (64), the threadson either end may be in opposite directions from one another to enable athreaded connection to a power module (320) without an external upsetalong the exterior of the motor. For example, the flangeless connection(64) may make up to the head module housing (134) via right handthreads, while the opposite end may make up to the power module housing(136) which contains left-hand threads. It will be appreciated thatright-hand threads turn in an opposing direction as compared toleft-hand threads. This connection may then be secured by locking aretaining nut (65) against the housing of the power module. Theconnection may also be secured using a set screw or other similarretaining method. As the connection is made, special alignment tools maybe used to ensure that the power terminals (63) and (68) and shaftcoupling are mated properly. The lower splines of the head module shaft(59) may connect to a coupling (135) designed to transmit torque fromthe shaft of the rotor (66) in the power module to the head module shaft(59). A bearing support (136) may be located in the upper end of a powermodule (320) where an upper HSSA bearing bushing (137) may be locatedand/or where a power module rotor (66) may be positioned.

As shown in FIG. 11, a wound stator core (72) may be positioned withinthe power module housing (67). The winding coils may be located insidethe stator core (72). A lower bearing support (75) may be positionedinside the power module housing (67) below the winding end coils (73).The lower bearing support (75) may be fitted with a HSSA Bearing bushing(76) and a corresponding HSSA Bearing sleeve (74). HSSA bearing sleeve(74) may be connected to a rotor (66).

In some embodiments, both the upper and lower end of the rotor (66) areassociated with axial thrust pads (79) which allow the rotor (66) toself-align within the magnetic field of the wound stator core (72).

A lower bearing support (75) may have mounting slots for the lowerterminals (138) from the wound stator core (72) above. In someembodiments, a lower portion of the power module housing (67) mayutilize a flangeless connection system similar to or substantially thesame as the flangeless connection previously mentioned.

As shown in FIG. 12, a motor base module (330) may comprise a basemodule housing (88), a hollow shaft (80) with a HSSA bearings sleeve, abearing support (83) with a HSSA bearing bushing, an impeller (84)and/or an adjustable axial thrust pad (85). In some embodiments, thebearing support (83) of the base module (320) may contain mountingpoints for the male terminals (82) that connect to the female terminalsof a lower power module. In some embodiments, terminals (82) may beconnected with a copper bus to create a wye point that connects allthree phases of the motor. A lower power module housing (86) may bemated to the base module housing (88) via a split ring (87) orflangeless connection system.

In some embodiments, the lower end of the rotor shaft (66) may be matedto a base module shaft (80) via a splined coupling (90).

In some embodiments, a centrifugal pump impeller (84) may be mounted onthe base module shaft (80). The impeller (84) may be fitted with anabrasive-resistant runner which may be configured to contact a thrustbearing (85). The thrust bearing (85) may have swiveling support (91)with a spring insert (92), which facilitates more uniform contact of thefriction surfaces of an axial bearing (93). The body of the axialbearing (93) may rest on a connecting coupling (94) and be fitted withan adjusting support (95) which may be used to adjust the axialclearance of the rotors throughout the motor system.

In some embodiments, the elements of the base module (320) may haveholes which form a channel for a sensor wire and/or a thermocouple to bepassed through. These wires may go through the central channel of aheat-exchanger module to a flange for a downhole sensor (10).

Connecting coupling body (97) may include an upper and/or lower threadwhich may be used to secure the base module housing (88) to a centralheat exchange module (410) exterior housing (98). Connecting coupling(97) may have tangential channels which may be used to direct the flowof lubricant into a pathway between the exterior housing (98) and theinterior housing (100) of the central heat exchange module (410). Insome embodiments, the flow in this pathway is in a spiral or helicalmotion due to the outer wall of the interior housing (100) having aguide vane connected in a helical path to direct the flow of lubricant.This helical pathway may be used to increase the residency time of thelubricant and increase the amount of heat transferred from the lubricantto the wellbore fluid. In some embodiments, the internal chamber of theinterior housing (100) may be comprise displacement rings (101) whichreduces the volume of the filling lubricant in the internal chamber ofthe exchanger. In some embodiments, the displacement rings (101) maycomprise a low coefficient of thermal expansion (CTE) material.

As shown in FIG. 13, once the lubricant reaches the bottom of thecentral heat exchange module (410) it may enter a connecting couplingvia a port (146) and crossover the connection through channels (147)which direct the flow into the outer channel of the lower heat exchangemodule (450) defined in part by lower heat exchange module exteriorhousing (148).

As shown in FIG. 14, the lower portion of the exterior housing (148) ofthe lower heat exchange module (450) may have a threaded connection witha bottom flange (149). The bottom flange may be used to connect adownhole sensor and may be fitted with a filling valve (150) which maybe used to fill the internal chamber of the heat exchanger withlubricant.

The lubricant may flow through the outer pathway (453) of the lower heatexchanger in order to dissipate heat from the lubricant to the exteriorhousing and into the well bore fluid. Then lubricant may flow from anouter pathway (453) of the lower heat exchange module (450) into theinterior of the lower heat exchange module via ports (151) and may bepassed by and/or through a magnet trap (152) to capture any particulate,such as, for example, ferrous wear debris. A lubricant return tube (153)may connect the base and head of the lower heat exchange module (450).In some embodiments, the lubricant return tube (153) may providerigidity and/or a mounting frame for displacement rings (154). Thelubricant return tube (153) may have several openings from the exteriorto the interior that may be covered with a fine mesh filter to reducethe number of impurities and/or non-ferrous materials that areintroduced into the motor. In some embodiments, this mesh filter may bea screen located at (500) with substantially uniform pore size. In someembodiments, the pores are at least about 10 μm, or at least about 20μm, or at least about 25 μm, or at least about 30 μm, or at least about40 μm wide. In some embodiments, the pores are at most about 10 μm, orat most about 20 μm, or at most about 25 μm, or at most about 30 μm, orat most about 40 μm wide.

As shown in FIG. 15, once the lubricant enters the return tube (153) itmay travel up through the return tubes of one or a plurality of centralheat exchange modules (410) through connecting tubes (155) and/orthrough a return path until it reaches the motor base module (330). Thecooled and filtered lubricant may then be returned through base moduleshaft (80) to the rotor (66) and then circulated up through the variousmotor modules and/or seal section before circulating back through thecentral (410) and lower (450) heat exchange modules.

It will be apparent to one of ordinary skill that elements of theexemplary embodiments described above may be utilized in alternateconfigurations, in alternate applications, with and/or without any ofthe other various elements described herein and otherwise known in theart. It will also be apparent that the various elements associated withany embodiment may be utilized with any other embodiment to achievesubstantially the same or an analogous result.

High Speed Electric Submersible Pump

Some embodiments of the disclosed inventions belong to the category ofequipment related to wellbore fluid production via artificial lift witha downhole submersible pumping unit. Some embodiments include apermanent magnet motor, which may be filled with a coolant and/orlubricant. In some embodiments, the disclosed pump may operate atgreater than about 3,000 RPM, or greater than about 5,000 RPM, orgreater than about 6,000 RPM, or greater than about 7,000 RPM, orgreater than about 9,000 RPM, or greater than about 10,000 RPM. In someembodiments, the disclosed pump may operate at less than about 3,000RPM, or less than about 5,000 RPM, or less than about 6,000 RPM, or lessthan about 7,000 RPM, or less than about 9,000 RPM, or less than about10,000 RPM.

Some embodiments of the disclosed inventions relate to an ESP assemblywhich is shorter than a standard ESP for a given flow rate and/or headpressure. In some embodiments, the length of a disclosed ESP is lessthan about 80 feet, or less than about 60 feet, or less than about 50feet, or less than about 45 feet, or less than about 42 feet, or lessthan about 35 feet, or less than about 30 feet, or less than about 25feet, or less than about 20 feet. In some embodiments, the length of adisclosed ESP is more than about 80 feet, or more than about 60 feet, ormore than about 50 feet, or more than about 45 feet, or more than about42 feet, or more than about 35 feet, or more than about 30 feet, or morethan about 25 feet, or more than about 20 feet. In some embodiments, thelength of a disclosed ESP is greater than about 80 feet, or greater thanabout 60 feet, or greater than about 50 feet, or greater than about 45feet, or greater than about 42 feet.

Certain embodiments relate to an ESP assembly comprising a pump module,wherein the pump module comprises a pump shaft and an impeller orimpellers, wherein the pump shaft is operably connected to a motor shaftand wherein the impeller is rotationally fixed to the pump shaft by akeyway. In some embodiments, the ESP further comprises a gas separatormodule and/or an intake module wherein the gas separator comprises a gasseparator shaft and an inducer, wherein the gas separator shaft isoperably connected to the motor shaft and the inducer is rotationallyfixed to the gas separator shaft by a keyway. In some embodiments, theinducer is a variable pitched inducer. In some embodiments, the ESPfurther comprises a seal section located between a motor module and thepump module, wherein the seal section is configured to transmit torquefrom the motor shaft to the pump shaft and absorb thrust from the pumpmodule. In some embodiments, the ESP further comprises a motor module,wherein the motor module comprises an AC electric permanent magnet motorconfigured to operate at a desired rpm, the motor configured to rotate amotor shaft and/or a motor cooling system, wherein the motor coolingsystem comprises a motor cooling impeller, the motor cooling impellerconfigured to circulate lubricant through a motor module heat exchangerwherein the motor module heat exchanger comprises a motor modulelubricant pathway, the motor module lubricant pathway configured toincrease a residence time of the lubricant in the motor module heatexchanger.

In some embodiments, the ESP assembly can be installed in a well with acasing having a drift ID of less than about 8 inches, less than about 7inches, less than about 6 inches, less than about 5 inches, or less thanabout 4.6 inches, or less than about 4.1 inches. In some embodiments,the ESP assembly can be installed in a well with a casing having a driftID of more than about 8 inches, more than about 7 inches, more thanabout 6 inches, more than about 5 inches, or more than about 4.6 inches,or more than about 4.1 inches. In some embodiments, the ESP assembly canbe installed in a well with a casing having a drift ID of about 4.6inches.

In some embodiments, the ESP assembly has a total dynamic head (TDH) infeet to length in feet ratio of at least about 80, or at least about100, or at least 150, or at least about 200, or at least about 220, orat least about 230, or at least about 250, or at least about 300. Insome embodiments, the ESP assembly has a TDH to length ratio of at mostabout 80, or at most about 100, or at most 150, or at most about 200, orat most about 220, or at most about 230, or at most about 250, or atmost about 300.

In some embodiments, the ESP assembly has a break horse power (BHP) tolength in feet ratio of at least about 4, or at or at least about 5, orat least about 7, or at least about 9, or at least about 10, or at leastabout 10.5, or at least about 12. In some embodiments, the ESP assemblyhas a BHP to length ratio of at most about 4, or at or at most about 5,or at most about 7, or at most about 9, or at most about 10, or at mostabout 10.5, or at most about 12.

In some embodiments, the ESP produces at least about 400 barrels per day(bpd), or at least about 1,000 bpd, or at least about 2,000 bpd, or atleast about 2,500 bpd, or at least about 3,000 bpd, or at least about3,500 bpd, or at least about 4,000 bpd, or at least about 5,000 bpd, orat least about 6,000 bpd, or at least about 7,000 bpd, or at least about7,500 bpd. In some embodiments, the ESP produces at most about 400barrels per day (bpd), or at most about 1,000 bpd, or at most about2,000 bpd, or at most about 2,500 bpd, or at most about 3,000 bpd, or atmost about 3,500 bpd, or at most about 4,000 bpd or at most about 5,000bpd, or at most about 6,000 bpd, or at most about 7,000 bpd, or at mostabout 7,500 bpd. Some embodiments are configured to produce betweenabout 1,000 and about 3,000 bpd without changing the downhole equipment.Preferred embodiments are configured to produce between about 400 andabout 4,000 bpd without changing the downhole equipment. As disclosedembodiments are configured to operate over a wide range of productionvolumes, the same ESP may be used as well production varies. Over thelife of an oil and gas well, production may slow. Traditionally, thishas required removing one ESP, configured to produce greater volumes offluid and replacing it with a different ESP configured to produce lowervolumes of fluid. This process may be repeated multiple times as thewell produces smaller volumes. Each time an ESP or other down holecomponent is changed or replaced, the corresponding surface equipmentmay also need to be replaced. Each of these steps can lead to down time,lost or deferred production, and increased inventory requirements.Additionally, there is a risk of losing the well each time it is sealedso that equipment may be removed and/or reinstalled. These downsides canbe reduced and/or avoided by utilizing disclosed embodiments whichoperate over a wide range of production volumes, thereby reducing oreliminating the need to change downhole equipment and/or correspondingsurface equipment.

In certain preferred embodiments, the disclosed ESP can be installed inwells where the casing has a drift ID of about 4.6 inches, producesgreater than 3,000 barrels per day (bpd), has a TDH in feet to length infeet ratio of at least about 100 and a BHP to length in feet ratio of atleast about 5.

In some embodiments of the disclosed ESP assembly, the seal sectioncomprises a port in fluid communication with the exterior environmentsurrounding the seal section and in fluid communication with an interiorchamber or multiple chambers, the interior chamber configured to reducea pressure differential between the exterior of the assembly to theinterior of the assembly.

In some embodiments of the disclosed ESP assembly the seal sectioncomprises a seal section cooling system wherein the seal section coolingsystem comprises a seal section heat exchanger wherein the seal sectionheat exchanger comprises a seal section lubricant pathway, the sealsection lubricant pathway configured to increase a residence time of thelubricant in the seal section heat exchanger. In such embodiments theseal section may further comprise a seal section lubricant return path.

In some embodiments of the disclosed ESP assembly the seal section andmotor lubricant pathways are linked and a single heat exchanger systemis utilized to cool both the seal section and the motor module. In suchembodiments, the motor lubricant return path may also be linked to theseal section lubricant return path in order to create a continuousand/or linked heat exchange assembly for both the seal section and motormodule.

Some embodiments of the disclosed ESP assembly comprising at least oneor more than one high-speed self-aligning bearing.

In some embodiments of the disclosed ESP assembly, the motor module heatexchanger comprises an upper heat exchange module and a lower heatexchanger module, the lower heat exchange module comprising a screenconfigured to trap non-ferrous particles and a magnetic trap configuredto trap ferrous particles.

In some embodiments of the disclosed ESP assembly, the seal sectioncomprises a thrust chamber wherein the thrust chamber comprises at leasttwo thrust bearings and wherein each thrust bearing is fitted with aspring damper designed to distribute a thrust load across two thrustbearings. In some embodiments, the spring damper may be designed todistribute the thrust load of the pump across two thrust bearingssubstantially evenly.

In some embodiments of the disclosed ESP assembly, the motor modulecomprises a head module, power module, and base module. In someembodiments, the motor module comprises more than one power module. Thenumber of power modules may be adjusted depending on the powerrequirements of the ESP for a given application.

In some embodiments of the disclosed ESP assembly, at least two powermodules are disposed between the head module and base module and aflangeless connection is used to connect the two power modules to eachother. In some embodiments, a flangeless connection is used to connectthe head module to a power module and/or to connect the base module to apower module.

In some embodiments of the disclosed ESP assembly, the motor modulefurther comprises a stator with a magnetic field wherein the motor rotoris configured to self-align within the magnetic field of the stator.

Some embodiments of the disclosed ESP further comprise an axial seatingsystem, configured to seat a motor rotor. In some embodiments, the axialseating of the rotor within the magnetic field of the stator may varythroughout the operating range of the system. The axial load faces mayhave slightly different microhardness in order for material to beremoved from the lower microhardness face, if and as needed, for therotor to seat at a given operating point. In axial thrust assemblies,the dynamic face preferably has a higher microhardness than the staticface and the static face is preferably of higher compressive strengththan that of the dynamic face. The methods and techniques described inASTM C1424-15, Standard Test Method for Monotonic Compressive Strengthof Advanced Ceramics at Ambient Temperature, may be used to determinethe compressive strength of a material.

In some embodiments, the dynamic face of an axial thrust assemblycomprises materials with a compressive strength of at least about 3,500Mpa, or at least about 3,700 Mpa, or at least about 4,000 Mpa, or atleast about 4,200 Mpa, or at least about 4,500 Mpa. In some embodiments,the dynamic face of an axial thrust assembly comprises materials with acompressive strength of at most about 3,500 Mpa, or at most about 3,700Mpa, or at most about 4,000 Mpa, or at most about 4,200 Mpa, or at mostabout 4,500 Mpa.

In some embodiments, the static face of an axial thrust assemblycomprises materials with a compressive strength of at least about 7,200Mpa, or at least about 7,500 Mpa, or at least about 7,800 Mpa, or atleast about 8,000 Mpa, or at least about 8,200 Mpa. In some embodiments,the static face of an axial thrust assembly comprises materials with acompressive strength of at most about 7,200 Mpa, or at most about 7,500Mpa, or at most about 7,800 Mpa, or at most about 8,000 Mpa, or at mostabout 8,200 Mpa.

In some embodiments, a rotor may be equipped with an axial load face onboth the upper and lower ends of the rotor body. The correspondingstator may be equipped with a complementary upper and lower load faceconfigured to absorb and distribute the load to the stator housing wheninteracting with the rotor surfaces. This arrangement allows the rotorto be preferentially aligned within the magnetic field of the statorthroughout its operating range.

Active Cooling System

In some embodiments, an active cooling system is utilized to reduce ormaintain the motor temperature and/or lubricant temperature. Disclosedactive cooling systems may be utilized with a variety of motors,including, for example, permanent magnet motors and/or induction motorsand/or may be utilized with a seal section or other non-motor machinery.It will be appreciated that features and elements of the disclosedactive cooling system may be used with other disclosed embodiments aswell as other equipment and/or machinery.

In some embodiments, a motor with the disclosed active cooling systemcomprises an electric motor, an impeller, at least one central heatexchanger module, and a lower heat exchanger module. Each heat exchangermodule typically comprises a head and a base. In disclosed embodiments,the impeller may be arranged to drive lubricant into a central heatexchanger. As shown in FIGS. 16 A-C, in some embodiments the centralheat exchanger module (410) comprises an exterior housing (412), aninterior housing (415), and a lubricant return tube (417) connected tothe head and base of each central heat exchanger module. The interiorhousing (415) is positioned within the exterior housing (412) andarranged to create a central heat exchanger lubricant pathway (418)between the interior and exterior housing. The lubricant pathway (418)allows a thin layer of lubricant to pass between the interior andexterior housings. This creates a thermal pathway allowing heat to betransferred from the lubricant to the exterior housing and then to thewellbore fluid. In many embodiments, the lubricant pathway (418) isarranged in a helical pattern, which causes the lubricant to flow aroundthe helical pathway, thereby increasing the residence time that thelubricant spends in the heat exchanger and allowing more heat to betransferred from the lubricant to the exterior housing and wellborefluid. In some embodiments, this helical pathway is created using a wireor similar material wrapped around the exterior of the interior housing(415). Additionally or alternatively, a wire may be wrapped around theinterior of the exterior housing, thereby creating a helical lubricantpathway between the interior housing and exterior housing. In preferredembodiments, the helical pathway is created by machining a pathway intothe exterior of the interior housing (415).

In some embodiments, the lubricant pathway (418) defined by the spacebetween the interior and exterior housing is at least about 0.04 inches,or at least about 0.06 inches wide, or at least about 0.065 inches wide,or at least about 0.07 inches wide, or at least about 0.1 inches wide,or at least about 0.25 inches wide or at least about 0.5 inches wide. Insome embodiments, the lubricant pathway (418) defined by the spacebetween the interior and exterior housing is at most about 0.04 inches,or at most about 0.06 inches wide, or at most about 0.065 inches wide,or at most about 0.07 inches wide, or at most about 0.1 inches wide, orat most about 0.25 inches wide or at most about 0.5 inches wide. Inpreferred embodiments, lubricant pathway (418) is about 0.0675 incheswide.

As shown in FIGS. 17 A, B, and C, in some embodiments, a lower heatexchanger (450) comprises a lower exterior housing (452), a lowerinterior housing (455), and a lower lubricant return tube (457). Thelower interior housing (455) may be disposed within the lower exteriorhousing (452). This arrangement creates a lower heat exchanger lubricantpathway (458) between the interior and exterior housings. The lowerlubricant return tube (457) may be disposed within the lower interiorhousing (455) and be in fluid communication with the lower heatexchanger lubricant pathway (458). As cooling lubricant circulatesthrough the lower heat exchanger (450), it flows into the lowerlubricant return tube (457), which may be fluidly connected to a centrallubricant return tube (417) which circulates lubricant to the top of thecentral heat exchanger (410) and back through the motor. The centralheat exchanger (410) may be connected to the lower heat exchanger (450)such that the central heat exchanger lubricant pathway (418) is fluidlyconnected to the lower heat exchanger lubricant pathway (458) and thecentral lubricant return tube (417) is in fluid communication with thelower lubricant return tube (457). This arrangement allows lubricant tobe circulated through the motor and heat exchangers in order to cool themotor and transfer heat from the motor components to the wellbore fluidvia the circulating lubricant and heat exchange modules. One or morescreens may be located at (500).

In some embodiments, multiple central heat exchanger modules may bearranged in a series. The central heat exchanger modules may beconfigured such that the lubricant return tube within the interiorhousing of each central heat exchanger is connectable to the lubricantreturn tube of a central heat exchanger module above and/or below. Theheat exchanger lubricant pathways of each central heat exchanger modulemay also be configured such that it is connectable with the heatexchanger lubricant pathways of the central heat exchanger modules aboveand/or below as well. This modular arrangement allows the disclosedactive cooling system to be customized based on the needs of a givenapplication. When a greater degree of cooling is needed, additionalcentral heat exchanger modules may be incorporated into the total motorsystem. This increases the length of the combined lubricant pathway,thereby increasing residence time and allowing a greater amount of heatto be transferred from the lubricant to the wellbore fluid. Inapplications where total length is a significant concern, a single lowerheat exchanger module may be utilized without any central heat exchangermodules. In such embodiments, the lower heat exchanger may be connectedto the motor base module. It will be appreciated that the lower heatexchanger module includes a lubricant pathway between the interiorhousing and exterior housing which dissipates heat from the lubricant tothe well bore fluid and also serves to direct lubricant flowing throughthe lubricant pathway into the lubricant return tubes. This allowslubricant to be circulated throughout either one or a series of heatexchanger modules before being directed back through the motor and/orseal section. In particularly hot wells, additional heat exchangermodules may be added to maintain the motor temperature within a desiredrange.

In an exemplary embodiment, the disclosed active cooling system may beused in an ESP comprising a motor housing, a stator, and a rotor shaft.In this exemplary embodiment, the rotor shaft comprising an interior andan exterior and the interior of the rotor shaft is in fluidcommunication with the lubricant return tube of the lower and/or centralheat exchange module. The rotor shaft may be arranged such thatlubricant flows from the lubricant return tube through the interior ofthe rotor shaft into the interior of the motor housing between the motorhousing and the stator. In some embodiments, the stator may comprisechannels which are designed to accommodate the flow of lubricant betweenthe stator and the motor housing.

Some embodiments of the disclosed active cooling system comprise afilter and/or magnetic trap configured to remove particles from thecirculating lubricant. In some embodiments, the lower heat exchangermodule comprises a screen designed to remove particles includingnon-ferrous wear products from the circulating lubricant. In someembodiments, the lower heat exchanger module comprises a magnetic trapdesigned to remove ferrous particles, including wear products from thecirculating lubricant. By removing particles, including ferrous andnon-ferrous wear product from the circulating lubricant, the activecooling system helps to maintain the quality of the circulatinglubricant. This leads to a longer service life of the overall systemincorporating the active cooling embodiments disclosed. ESPs whichcomprise the disclosed active cooling system with screen filter andmagnet trap may have a longer service life than traditional ESPs,resulting in improved run life and service time.

In exemplary embodiments, the disclosed active cooling system is used inan ESP. In such embodiments, when the circulating lubricant reaches thetop of the upper central heat exchanger module lubricant return tube, itthen enters the interior of a motor base shaft and rotor shaft. In someembodiments, the motor base shaft and rotor shaft as part of thelubricant return pathway. The circulating lubricant flows up the rotorshaft to the top of the motor. In some embodiments, the rotor shaftincludes holes from the interior of the shaft to the exterior wherebushings or other components which may benefit from cooling and/orlubrication are located. These holes allow circulating lubricant tocontact bushings, bearings, or other components in order to cool and/orlubricate the components. The lubricant then continues to be circulatedthrough the active cooling system.

In some embodiments, lubricant flows up the rotor shaft of the motor andinto the shaft of the seal section. At that point, the lubricant may bedirected out of the seal section shaft through holes leading from theinterior of the shaft to the exterior where bushings or other componentswhich may benefit from cooling and/or lubrication may be located. Insome embodiments, lubricant may be directed out of the seal sectionshaft by an impeller located on or near the top of the lubricant flowpath. The impeller may drive the circulating lubricant through holesleading from the interior of the shaft to the exterior of the shaft. Insome embodiments, the lubricant may then flow through the motor moduleand/or enter the linked lubricant pathway between the interior andexterior housings of the seal section and motor module to dissipate heatbefore being recirculated through the motor module and seal section.

In some embodiments, once circulating lubricant reaches the top of themotor module, prior to reaching the seal section, the lubricant may bedirected out of the rotor shaft by an impeller located on the top of therotor. The impeller drives the circulating lubricant through exit holesleading from the interior of the rotor shaft to the exterior of therotor shaft.

In some embodiments, lubricant channels located between the stator andthe motor housing direct circulating lubricant between the stator andthe housing and may, in some embodiments, direct lubricant through slotsof the wound stator core. This path allows lubricant to pick up heatfrom the interior of the rotor shaft as well as the stator and motorhousing. Once the lubricant has flown down the motor, between the statorand housing, the circulating lubricant enters the lubricant pathway ofthe upper central heat exchanger module where heat may be dissipated tothe exterior housing of the head exchanger module and the wellbore fluidin contact with the outside of the exterior housing.

Modular Motor System and Flangeless Connection

As can be seen in FIG. 10A, in some embodiments, the motor system isbuilt in modules that consist of a head module, a power module and abase module. In some embodiments, multiple power modules may beconnected via a flangeless connection system in order to reach thedesired application power requirements. It will be appreciated that thedisclosed module systems and connections may be utilized with any otherdisclosed element or embodiment as well as with other equipment and/ormachinery.

In some embodiments, two modules may be connected to each other using aflangeless connection (510). As shown in FIG. 18, in some embodiments,the flangeless connection (510) comprises a single piece housingcoupling (512), a lock nut (515), and a spacer ring (518). In someembodiments using the flangeless connection, the two components ormodules being joined will have opposite handed threads which turn indifferent directions. For example, if the lower end of a first powermodule is to be joined to the upper end of a second power module, thelower end of the first power module may comprise left-handed threadswhile upper end of the second power module may comprise right handedthreads. In some embodiments, the single piece housing couplingcomprises opposite handed threads on its upper and lower ends.

In some embodiments, the lock nut and spacer may be installed on thehousing coupling. The upper and lower modules to be joined may beengaged with the threads on the single piece housing coupling andsimultaneously madeup as the single piece housing coupling is rotated.Once completely madeup the lock nut may be tightened against the spacerring. Depending on the application, once the modules and/or componentsare threadedly attached, the components may be secured by welding oranother method known to prevent unthreading known in the art.

Some disclosed embodiments relate to a motor for an electric submersiblepump assembly, the motor comprising a head module; a base module; and atleast two power modules disposed between the head module and basemodule. In some embodiments, each power module comprises a power modulehousing having an upper and lower portion; and at least two powermodules are connected to each other using a flangeless connection, theflangeless connection comprising a housing coupling, a lock nut, and aspacer ring. In some embodiments, a power module may be connected to abase module and/or a head module using the disclosed flangelessconnection regardless of the number of power modules in the ESPassembly.

In some embodiments, the upper portion of the power module housingscomprise threads rotating in a certain direction, for example, righthanded threads, and the lower portion of the power module housingscomprise threads rotating in the opposite direction, for example, lefthanded threads. In some embodiments, the housing coupling comprises anupper portion and a lower portion, the upper portion of the housingcoupling having right or left handed threads to connect to the lowerportion of a power module housing and the lower portion of the housingcoupling having opposite handed threads to connect to the upper portionof a power module housing.

Disclosed embodiments of the flangeless connection may help to maximizethe available motor diameter. The disclosed flangeless connection alsoreduces and/or eliminates choke points that may inhibit the flow ofmotor oil, lubricant, and/or dielectric fluid. Embodiments of thedisclosed flangeless connection increase the available heat exchangersurface area, thereby allowing greater amounts of heat to be transferredfrom the motor or other components to the wellbore fluids. Disclosedembodiments also allow the various modules to be coupled in amanufacturing facility rather that at the well site environment. Thisallows the operator to save time installing an ESP utilizing thedisclosed features and leads to increased reliability of the assembledESP and/or other components.

HSSA Bearing Details

In some embodiments, the disclosed ESP components, as well as otherequipment, motors, and/or machinery may comprise high-speedself-aligning (HSSA) bearings. It will be appreciated that the disclosedbearing design may be utilized with any of the disclosed elements orembodiments as well as with other equipment or machinery.

In some embodiments, a module may be equipped with a radial bearing withthe dynamic portion of the bearing (the bearing sleeve) beingrotationally fixed to a rotating shaft. In such embodiments, the statormay be equipped with a complementary static portion (the bushing) whichabsorbs and distributes a radial load to the stator housing. The sleevecomprises material which may have a lower microhardness than thebushing. This arrangement allows for the sleeve (the dynamic face) to“wear-in” if necessary in order to reach an improved and/or optimumoperating point. In some embodiments, the sleeve will be attached to arotor which is contained in the magnetic field of the stator. Thedisclosed arrangement allows the rotor to reach an improved or optimumposition within the magnetic field of the stator.

In some embodiments, the sleeve or a sleeve portion of a sleeve assemblymay comprise carbide. In certain embodiments, the sleeve comprisestungsten carbide with at least about 4% nickel, or at least about 5%nickel, or at least about 6% nickel, or at least about 7% nickel. Incertain embodiments, the sleeve comprises tungsten carbide with at mostabout 4% nickel, or at most about 5% nickel, or at most about 6% nickel,or at most about 7% nickel.

In some embodiments, the bushing may be mounted on a fixed support usingone or multiple elastomeric bands. In some embodiments, the elastomericbands comprise materials that, when in contact with a coolant,lubricant, and/or dielectric fluid, they will expand and lock thebushing to the support. In some embodiments, the elastomeric bands donot allow any axial or rotational movement of the bushing. In someembodiments, the anchoring strength on the bushing may be increased byadding a groove or helical groove on the outside of the bushing, therebyallowing the bands to “grip” the bushing. The elastomeric band may alsohelp to center the bushing in the bushing support and/or provide adampening effect in the event of any vibration.

In some embodiments, the bushing may have grooves which allow lubricantto flow between the static and dynamic bearing faces. In radialbearings, the static face is the bushing and the dynamic face is thesleeve. These grooves allow lubricant to flow between the bushing andthe sleeve and clear any particulate or debris, such as, for example,debris caused by wearing of the bearing faces. In some embodiments, thelubricant cooling and/or circulation system may comprise a screen and/ormagnetic trap to remove such debris as the lubricant is circulated.

In some embodiments, the bushing may comprise an outer bushing body anda bushing insert. The outer body may comprise a low CTE material. Thebushing insert comprises a material of a higher microhardness than theassociated sleeve.

In some embodiments, a multi-piece bushing may allow for thinnermaterials to be used. One advantage of thinner materials is that ahigher proportion of any thermal growth will be in the axial planerather than the radial plane. This arrangement allows tight tolerancesto be maintained at high speeds and high temperatures.

As shown in FIG. 19, in some embodiments, a sleeve assembly (530)comprises a sleeve body (533) and at least two sleeves (535). In suchembodiments, the sleeve body (533) and each sleeve (535) comprises akeyway. In some embodiments, the two sleeves (535) may be mounted ontothe sleeve body (533) and the sleeve assembly (530) may be mounted ontoa rotating shaft using the keyways and associated keys. In someembodiments, the sleeve assembly further comprises an inside limitingnut which may be threaded onto a rotating shaft and limit axial movementof the sleeve assembly. In some embodiments, the limiting nut may holdthe keys, for example “L” keys, in the keyway while the sleeve assemblyis mounted onto a shaft.

In some embodiments, a tapered centralizing ring may be mounted with aset of keys to provide centralization of the sleeve assembly on theshaft. In some embodiments, an outside limiting nut may be threaded intoplace but may be stopped prior to contacting the tapered centralizingring. This arrangement allows for the sleeve assembly to have a smallamount of axial movement between the inside and outside limiting nuts inorder to assist in the bearing finding an improved or optimum operatingpoint. Once the outside limiting nut is in place the edges of thetapered centralizing ring may be peened into a machined groove on theoutside limiting nut.

In some embodiments, a rotor shaft may have elastomeric bands which asleeve assembly fits around. These elastomeric bands may help to directlubricant from the interior of the shaft to the exterior of the sleevebody and onto the face of the sleeves. This arrangement allows lubricantcirculating within the rotor shaft to lubricate and cool the bearingfaces. The elastomeric bands may also help to center the sleeve assemblyand dampen any vibration.

In some embodiments, a pump and/or gas separator may comprise HSSAbearings. An HSSA bearing for a pump may be comprise of a bushing and asleeve. The bushing may be held onto a bushing support by aninterference fit or any other technique known in the art. In someembodiments, elastomeric bands maybe used to prevent rotation of thebushing, the help center a shaft, and/or to dampen vibration.

In some embodiments a two-piece sleeve may be used. A two-piece sleevemay comprise an outer sleeve and an inner sleeve. The outer sleeve maybe keyed to the inner sleeve in order to rotationally fix the inner andouter sleeves of the two-piece sleeve. In some embodiments, the outersleeve may be fluted and/or comprise a helical groove on the exterior toallow for the removal of particulate or other contaminants and/or topromote the flow of lubricant. In some embodiments, the inner sleeve maybe keyed to a shaft via a dual keyway. The inner sleeve may comprise lowCTE materials designed to help reduce thermal growth in the radialdirection. This arrangement may allow the outer sleeve to be thinnerwhich further reduces radial thermal growth.

In some embodiments, the design of the high-speed self-aligning (HSSA)radial bearings may be based on the concept that at high rotationalspeed the dynamic face (the rotating sleeve) performs better afterfinding its optimal or improved running position within the static face(the non-rotating bushing).

To facilitate this process, the materials of the sleeve and bushingshould have slightly different microhardness in order for material to beremoved from the lower microhardness face, if or as needed, for thebearing to self-align. The sleeve material may additionally be of ahigher flexural strength than the bushing material in order to allow itto overcome any bending stresses encountered during the process ofself-alignment. To further facilitate the process of self-alignment, insome embodiments, the sleeve assembly may be allowed to move, at leastto a degree, in the axial direction. In some embodiments, the sleeveassembly may be allowed to move at least about 20 mils, or at leastabout 25 mils, or at least about 30 mils, or at least about 40 mils, orat least about 50 mils, or at least about 60 mils, or at least about 70mils, or at least about 75 mils. In some embodiments, the sleeveassembly may be allowed to move at most about 20 mils, or at most about25 mils, or at le most ast about 30 mils, or at most about 40 mils, orat most about 50 mils, or at most about 60 mils, or at most about 70mils, or at most about 75 mils.

Some embodiments of the disclosed inventions relate to a radial bearingassembly suitable for mounting on a rotatable shaft, the radial bearingassembly comprising one or more radial bearings, each bearing comprisinga bushing and a sleeve, the bushing and sleeve each comprising aninterior and an exterior. The interior of the bushing being inlubricated, engagement with the exterior of the sleeve, wherein thebushing is affixable to a non-rotatable bushing support and comprises amaterial having a higher microhardness than the sleeve and wherein thesleeve is configured to mount to a rotating shaft and comprises amaterial having a higher flexural strength than the bushing. In someembodiments, the bushing comprises a material having a microhardness ofat least about 2,000 MPa, or at least about 2,500 MPa, or at least about2,800 MPa, or at least about 3,000 MPa, or at least about 3,200 MPa onthe Knoop microhardness scale. In some embodiments, the bushingcomprises a material having a microhardness of at most about 2,000 MPa,or at most about 2,500 MPa, or at most about 2,800 MPa, or at most about3,000 MPa, or at most about 3,200 MPa on the Knoop microhardness scale.In some embodiments, the sleeve comprises a material having amicrohardness of at least about 1,000 MPa, or at least about 1,500 MPa,or at least about 1,800 MPa, or at least about 2,000 MPa, or at leastabout 2,200 MPa on the Knoop microhardness scale. In some embodiments,the sleeve comprises a material having a microhardness of at most about1,000 MPa, or at most about 1,500 MPa, or at most about 1,800 MPa, or atmost about 2,000 MPa, or at most about 2,200 MPa on the Knoopmicrohardness scale.

The methods and techniques described in ASTM C1326-13, Standard TestMethod for Knoop Indentation Hardness of Advanced Ceramics, may be usedto determine the microhardness of a material.

In some embodiments, the sleeve comprises a material having a flexuralstrength of at least about 1,000 Mpa, or at least about 1,300 Mpa, or atleast about 1,500 Mpa, or at least about 1,800 Mpa, or at least about2,000 Mpa. In some embodiments, the sleeve comprises a material having aflexural strength of at most about 1,000 Mpa, or at most about 1,300Mpa, or at most about 1,500 Mpa, or at most about 1,800 Mpa, or at mostabout 2,000 Mpa. In some embodiments, the bushing comprises a materialhaving a flexural strength of at least about 300 Mpa, or at least about300 Mpa, or at least about 400 Mpa, or at least about 450 Mpa, or atleast about 500 Mpa. In some embodiments, the bushing comprises amaterial having a flexural strength of at most about 300 Mpa, or at mostabout 300 Mpa, or at most about 400 Mpa, or at most about 450 Mpa, or atmost about 500 Mpa.

The methods and techniques described in ASTM C1161-02c(2008)e1, StandardTest Method for Flexural Strength of Advanced Ceramics at AmbientTemperature, may be used to determine the flexural strength of amaterial.

In some embodiments, the bushing interior comprises a plurality ofgrooves configured to allow lubricant to flow between the bushing andthe sleeve and wherein the grooves are configured to discharge debris.In some embodiments, the grooves are at least about 3.0 mm wide, or atleast about 4.0 mm wide, or at least about 4.5 mm wide, or at leastabout 5.0 mm wide. In some embodiments, the grooves are at most about3.0 mm wide, or at most about 4.0 mm wide, or at most about 4.5 mm wide,or at most about 5.0 mm wide. In certain embodiments, the grooves areabout 4.73 mm wide.

In some embodiments, as shown in FIGS. 20A and 20B, the bushing (550)has a surface feature (553) configured to distribute lubricant as thesleeve rotates. The bushing (550) may have an groove, configured tofacilitate and/or maintain the build-up of lubricant to be distributedonto the interface of the bushing (550) and sleeve. This surface feature(553) may facilitate removal of particulate. In some embodiments, thissurface feature (553) has a larger radius on the leading edge than thetrailing edge.

In some embodiments, the radial bearing assembly further comprises anelastomeric band disposed between the bushing exterior and bushingsupport, the elastomeric band configured to expand when in contact witha lubricant and prevent substantial deleterious movement of the bushingrelative to the bushing support. In some embodiments, deleteriousmovement comprises radial and axial movement. In some embodiments, asshown in FIG. 20A, the radial bearing assembly may further comprise agroove (555) in the bushing exterior wherein the groove is configured toincrease binding between the bushing and the elastomeric band. In someembodiments, the groove is helical and the elastomeric band isconfigured to dampen vibration.

In some embodiments of the radial bearing assembly, the sleeve isaxially movable between about 1.5 mm and about 3.0 mm relative to therotating shaft. In some embodiments, the sleeve may be axially movablerelative to the rotating shaft by at least about 0.5 mm, or at leastabout 0.8 mm, or at least about 1.0 mm, or at least about 1.5 mm, or atleast about 2.0 mm, or at least about 2.5 mm, or at least about 3.0 mm,or at least about 3.5 mm, or at least about 4.0 mm. In some embodiments,the sleeve may be axially movable relative to the rotating shaft by atmost about 0.5 mm, or at most about 0.8 mm, or at most about 1.0 mm, orat most about 1.5 mm, or at most about 2.0 mm, or at most about 2.5 mm,or at most about 3.0 mm, or at most about 3.5 mm, or at most about 4.0mm. The allowed axial movement of the sleeve relative to the shaft mayallow a rotor shaft to find an improved or optimum position within themagnetic field of a stator.

In some embodiments of the radial bearing assembly, the sleeve comprisestwo outer sleeves and an inner sleeve body, wherein the two outersleeves and inner sleeve body each comprise a keyway. In someembodiments, the sleeve body and the rotating shaft each comprise aninterior and an exterior. The sleeve body may comprise an openingallowing lubricant to pass from the interior of the sleeve body to theexterior of the sleeve body and the shaft may comprise an openingallowing lubricant to pass from the interior of the shaft to theexterior of the shaft. One or more elastomeric bands may be disposedbetween the exterior of the shaft and the interior of the sleeve bodycreating a gap for the flow of lubricant from the interior of the shaftto the exterior of the sleeve body. In some embodiments, the assemblyfurther comprises a screen configured to be in fluid communication witha lubricant, the screen designed to remove wear products from thelubricant. In some embodiments, the assembly further comprises amagnetic trap configured to be in fluid communication with a lubricant,the magnetic trap designed to remove ferrous wear products from thelubricant

In some embodiments of the radial bearing assembly the bushing comprisesa bushing body and a bushing insert, wherein the bushing insertcomprises a material having a higher microhardness than the sleeve andwherein the bushing body comprises a low CTE material. In someembodiments of the radial bearing assembly the sleeve comprises an outersleeve and an inner sleeve, wherein the inner sleeve comprises a low CTEmaterial. In some embodiments, the low CTE material has a CTE of atleast about 3.5, or at least about 4.0, or at least about 4.5, or atleast about 5.0, or at least about 5.5 μm/m-° C. In some embodiments,the low CTE material has a CTE of at most about 3.5, or at most about4.0, or at most about 4.5, or at most about 5.0, or at most about 5.5μm/m-° C. In certain embodiments, the low CTE material has a CTE ofabout 4.9. Low cte materials may include, but are not limited to, forexample, Invar™, Inovco™, Kovar™, Rodar™, Telcoseal™, Sealvar™, Selvar™,Alloy 29-17™, Nilo K™, Dilver™, Pernifer 29-18™, Alloy 29-18™, Nicosel™,Nicoseal™, and/or Therlo™.

It will be appreciated that the disclosed bearings may be incorporatedinto any of the components and/or modules described herein including,but not limited to the pump modules, motor modules, gas separator,and/or seal section.

Symmetrical Rotor

Disclosed embodiments relate to or comprise a rotating rotor. In someembodiments, a symmetrical rotor may allow for a higher grade ofbalancing to reduce and/or minimize any mechanical vibration when therotor rotates at operating speeds. It will be appreciated that thedisclosed ESP embodiments may comprise a symmetrical rotor and that thefeatures and elements disclosed herein may be used with any otherequipment or machinery which utilizes rotating parts, pumps, motors,rotors, and/or stators. The alignment of various components, includingfor example, shaft splines, keyways, impellers, lubricant holes and/orbearing seats may all impact operation, particularly high-speedoperation. A symmetrical rotor may have designated bronze end rings forremoval of material to achieve a balance grade of G1 per ISOspecification 21940-11:2016. These end rings may be covered with sleevesmade of titanium or other materials and sealed with an anaerobic gasketin order to ensure that no material fills the area where material wasremoved which could lead to future imbalances. It will be appreciatedthat in some embodiments, the symmetrical rotor is verticallysymmetrical in addition to axially and/or radially symmetrical. In someembodiments, a vertically symmetrical rotor does not include an impellerat either end in order to ensure vertical symmetry. In such embodiments,any necessary impellers may be relocated to other areas of the disclosedESP assembly including, for example, the seal section and/or the top ofthe lubricant flow path.

Motor Base Thrust Module

Some disclosed embodiments comprise a motor base thrust module. It willbe appreciated that elements and feature of the disclosed thrust modulemay be applied to other embodiments as well as other equipment and/ormachinery. A thrust runner may be connected to an impeller in the motorbase. In some embodiments, a thrust runner is connected to the bottom ofan impeller that drives the motor active cooling system. In suchembodiments, the static face may be built into a body and/or assemblythat may be axially adjusted to compensate for any variation it theposition of the shafts of the power modules.

The static face of the motor base thrust module may be centrally mountedon a pivot head. In some embodiments, the static face may be tensionedusing springs that facilitate evenly spreading the load across thebearing. In some embodiments, between 2 and 8 springs may be used. Inpreferred embodiments, six springs may be used.

In some embodiments of the motor module base thrust module, the dynamicface of the thrust runner may comprise a material with a highermicrohardness than the material of the static face. In such embodimentsof the thrust module, the static face may comprise a material with alower microhardness than the dynamic face. The static face may alsocomprise a material compression of a higher compression strength thanthe material of the dynamic face.

One of many potential materials known to have a high compressionstrength is carbon graphite. Carbon graphite is beneficially known tohave high compression strength, low coefficient of friction andself-lubricating properties. Carbon graphite materials are known to havea high operational temperature limit which may be beneficial in someembodiments due to the increased friction heat generated by someembodiments of the disclosed pump assembly at higher speeds. Thrustwashers may additionally or alternatively comprise, for example,polymeric materials or other materials depending on the applicationconditions.

In some embodiments, the static and/or dynamic face of the motor basethrust module may comprise grooves. The grooves may be configured tofacilitate maintaining a lubricant film or layer between the static anddynamic faces of the motor base thrust module.

Motor Filter and Magnet Trap

Some disclosed embodiments comprise a filter and/or magnet trap forremoving non-ferrous and/or ferrous particulate. It will be appreciatedthat elements and feature of the disclosed filter and magnetic trap maybe applied to other embodiments as well as other equipment and/ormachinery.

Some embodiments of the disclosed motor system comprise a lower heatexchange module. The lower heat exchange module may comprise a shaftwith holes from the outer diameter to the inner diameter. The lower heatexchange module may comprise a filter medium to filter lubricant whichpasses through the holes. The filter medium may include, but is notlimited to screen mesh, fibrous mesh, or any other material capable offiltering non-ferrous contaminants from the circulating lubricant. Someembodiments may comprise a magnet trap configured to catch ferrousdebris or other particles that may be produced during the operation ofthe motor. In some embodiments, the magnet trap may be positioned nearthe bottom of the lubricant return tube in order to capture any ferrousparticles which may settle during circulation.

Dual Bearing Thrust Chamber and Integrated Heat Exchanger

Some disclosed embodiments comprise a dual bearing thrust chamber and/oran integrated heat exchanger. It will be appreciated that elements andfeature of the disclosed thrust chamber and heat exchanger may beapplied to other embodiments as well as other equipment and/ormachinery.

In some embodiments of the disclosed pump assembly, the seal sectioncomprises a dual bearing thrust chamber configured to absorb thrust fromthe pumps and transmit rotation from the motor to the pumps. In someembodiments, the dual bearing thrust chamber allows axial load to beevenly distributed across two thrust bearings, thereby substantiallydoubling the amount of thrust the seal chamber can absorb. In someembodiments of the disclosed pump assembly, the axial thrust generatedby the pumps is transferred entirely to the thrust bearings in the sealsection thrust chamber. In some embodiments, no axial thrust istransferred to any bearing which provides radial support.

In some embodiments, a thrust chamber arranged to transfer thrust from ashaft to a thrust bearing comprises a shaft that is operably connectedto at least one impeller. The impeller may be configured to generatedownward thrust when it is in operation. The thrust chamber alsocomprises a thrust chamber outer housing, a first thrust runner, that iscoupled to the shaft and comprises an upward facing thrust transferringsurface and a downward facing thrust transfer surface. The thrustchamber may also comprise a first thrust bearing assembly coupled to theouter housing; wherein the first thrust bearing assembly comprises anupward facing thrust receiving surface and wherein the first thrustrunner is configured to transfer downward thrust from the shaft to thefirst thrust bearing assembly. In some embodiments, an up-thrust bearingassembly may be coupled to the outer housing, wherein the up-thrustbearing assembly comprises a downward facing thrust receiving surfaceand wherein the first runner is configured to transfer upward thrustfrom the shaft to the up-thrust bearing assembly. In some embodiments, asecond thrust runner may be coupled to the shaft and comprise a downwardfacing thrust transfer surface and a second thrust bearing assembly maybe coupled to the outer housing, wherein the second thrust bearingassembly comprises an upward facing thrust receiving surface and whereinthe second thrust runner is configured to transfer downward thrust fromthe shaft to the second thrust bearing assembly. Some embodiments mayalso comprise a first and a second damper, wherein the first damper isconfigured to absorb downward thrust from the first thrust runner andtransfer the downward thrust to the first thrust bearing assembly andthe second damper is configured to absorb downward thrust from thesecond thrust runner and transfer the downward thrust to the secondthrust bearing assembly. In such embodiments, the dampers may beconfigured to spread axial load substantially evenly across at least twothrust bearings.

Preferred embodiments of the disclosed thrust chamber may comprise athrust chamber heat exchanger, wherein the thrust chamber heat exchangercomprises a thrust chamber interior housing and thrust chamber lubricantreturn path, wherein the thrust chamber interior housing is disposedwithin the thrust chamber outer housing and defines a thrust chamberheat exchanger lubricant pathway therebetween. In such embodiments thethrust chamber lubricant return path may be in fluid communication withthe thrust chamber lubricant pathway and may be disposed within theinterior housing.

In some embodiments, the shaft comprises an interior and an exterior,and the interior of the shaft may be in fluid communication with thelubricant return path. In some embodiments, the up-thrust bearingassembly comprises a static downward facing thrust receiving surface. Insome embodiments, the upward facing thrust receiving surfaces of thefirst and second thrust bearing assemblies have a higher microhardnessthan the downward facing thrust transfer surfaces of the first andsecond thrust runners.

In some embodiments, the dampers are configured to distributesubstantially even thrust load across the first and second thrustbearing assemblies. In some embodiments, the dampers may compriseBelleville washers and/or stacks of Belleville washers configured inparallel.

In some embodiments, the thrust chamber lubricant pathway issubstantially helical.

In some embodiments, the thrust chamber heat exchanger further comprisesa filter screen and/or a magnetic trap in fluid communication with thethrust chamber lubricant pathway

In some embodiments, the outer thrust housing is threadedly connected toa seal section, and the seal section is disposed between a motor moduleand a pump module. In some embodiments, the pump module comprises animpeller that generates downward thrust when in operation, and thedownward thrust generated by the impeller is communicated to the thrustchamber shaft and transferred by the first and second thrust runners tothe first and second thrust bearing assemblies which are axially fixedto the thrust chamber outer housing.

In certain embodiments, the lubricant pathway of the seal section thrustchamber may be in fluid communication with the lubricant pathway of themotor module heat exchangers, thereby creating a unified active coolingsystem for the motor assembly and seal section. In embodiments whichutilize at least one active cooling system, the cooler lubricant mayallow for a more viscous lubricant film to be maintained between anaxial thrust transferring and thrust receiving surface. This viscouslubricant layer may help extend the life of the seal section thrustchamber as well as the other thrust transferring and/or lubricatedcomponents.

In addition to being utilized to cool motors, the disclosed activecooling system may be utilized with a seal section. The disclosed sealsection may comprise an impeller, interior housing, exterior housing,and lubricant return path. The housings may be arranged to create a sealsection lubricant pathway between the interior and exterior sealhousings. Lubricant may be driven by the impeller to flow through thelubricant pathway, thereby dissipating heat from the lubricant to theexterior seal housing and wellbore fluid. The lubricant may then becirculated through the lubricant return path to the interior of the sealsection before circulating back through the lubricant pathway. Inpreferred embodiments, the disclosed seal section cooling systemscomprise a screen and magnetic trap to remove ferrous and non-ferrousparticles from the circulating lubricant.

In some embodiments, the disclosed active cooling system may be utilizedwith both a motor and seal section. In such embodiments, the sealsection lubricant pathway may be fluidly connected to the central heatexchangers of the motor section. The lubricant return tube of the lowerheat exchanger module may be fluidly connected to the lubricant returntubes of the central heat exchanger modules and also to the lubricantreturn path of the seal section heat exchanger modules. This arrangementallows circulating lubricant to cool and lubricate the components of theassociated motor and seal section. This arrangement further allowslubricant in the seal section to be cooled by as many heat exchangemodules as are required to maintain the desired operating temperaturerelative to the wellbore fluid. In some embodiments, the heat exchangermodules may be configured to maintain the temperature of the circulatinglubricant to less than about 15° C. above the temperature of thewellbore fluid, or less than about 10° C. above the temperature of thewellbore fluid, or less than about 7° C. above the temperature of thewellbore fluid, or less than about 5° C. above the temperature of thewellbore fluid. In some embodiments, the heat exchanger modules may beconfigured to maintain the temperature of the circulating lubricant tomore than about 15° C. above the temperature of the wellbore fluid, ormore than about 10° C. above the temperature of the wellbore fluid, ormore than about 7° C. above the temperature of the wellbore fluid, ormore than about 5° C. above the temperature of the wellbore fluid.

In some alternative embodiments of the disclosed pump assembly may bearranged to pump more wellbore fluid, and thereby generate more downwardthrust than some embodiments of the seal section thrust chamber isdesigned to absorb. In such embodiments, pump modules may be configuredto comprise a thrust runner and thrust absorbing assembly. In someembodiments, the pump module thrust absorbing assembly may beself-leveling. The pump module thrust absorbing assembly may comprisebushings and sleeves for radial support in addition to thrust runnersand thrust absorbing surfaces for absorbing axial support.

Gas Separator Inducer and Carbide Lined Separation Chamber

Some disclosed embodiments comprise a gas separator inducer and/or acarbide lined separation chamber. It will be appreciated that elementsand feature of the disclosed gas separator and separation chamber may beapplied to other embodiments as well as other equipment and/ormachinery.

In some embodiments, the disclosed ESP assembly comprises a gasseparator configured to separate gas phase and liquid phase. In someembodiments, the gas separator comprises an inducer, for example avariable pitch and/or helical inducer. In some embodiments, the inducermay comprise vanes inclined towards the liquid flow path. In someembodiments, a separation chamber may be lined with carbide insertsand/or comprise abrasion resistant materials configured to preventerosional wear from abrasive solids. Some embodiments of the disclosedgas separator may further comprise elastomeric bands connected to thecarbide inserts, the elastomeric bands configured to dampen and/ormitigate vibration.

It will be understood that the various disclosed embodiments mayincorporate some or all of the components described herein. Theparticular components and the properties thereof may be adjusted basedon the properties of each particular embodiment and applicationconditions. From the foregoing description, one of ordinary skill in theart can easily ascertain the essential characteristics of thisdisclosure, and without departing from the spirit and scope thereof andcan make various changes and modifications to adapt the disclosure tovarious usages and conditions. The embodiments described hereinabove aremeant to be illustrative only and should not be taken as limiting of thescope of the disclosure.

Representative Embodiments

ESP Embodiments

1. An electric submersible pump assembly, comprising:

a pump module, wherein the pump module comprises a pump shaft and animpeller, wherein the pump shaft is operably connected to a motor shaftand wherein the impeller is rotationally fixed to the pump shaft by akeyway;

a seal section, wherein the seal section is configured to transmittorque from the motor shaft and absorb thrust from the pump module;

a motor module, wherein the motor module comprises a motor configured tooperate at greater than 4,000 rpm, the motor configured to rotate amotor shaft; and

a motor cooling system, wherein the motor cooling system comprises amotor cooling impeller, the motor cooling impeller configured tocirculate lubricant through a motor module heat exchanger wherein themotor module heat exchanger comprises a motor module lubricant pathway,the motor module lubricant pathway configured to increase a residencetime of the lubricant in the motor module heat exchanger.

2. The assembly of embodiment 1, further comprising a gas separatormodule wherein the gas separator comprises a gas separator shaft and aninducer, wherein the gas separator shaft is operably connected to themotor shaft and the inducer is rotationally fixed to the gas separatorshaft by a keyway.

3. The assembly of embodiment 1, further comprising a fluid in-take.

4. The assembly of embodiment 1, wherein the seal section comprises aport in fluid communication with the exterior environment surroundingthe seal section and in fluid communication with an interior chamber,the interior chamber configured to reduce a pressure differentialbetween the pressure from the exterior of the assembly to the interiorof the assembly.

5. The assembly of embodiment 1, wherein the seal section comprises aseal section cooling system wherein the seal section cooling systemcomprises a seal section heat exchanger wherein the seal section heatexchanger comprises a seal section lubricant pathway, the seal sectionlubricant pathway configured to increase a residence time of thelubricant in the seal section heat exchanger.

6. The assembly of embodiment 5, wherein the seal section lubricantpathway is in fluid communication with the motor module lubricantpathway

7. The assembly of embodiment 1, further comprising a high-speedself-aligning bearing, the high-speed self-aligning bearing comprising abushing and a sleeve, the bushing having a microhardness of at leastabout 2,500 MPa and the sleeve having a microhardness of at most about2,000 MPa

8. The assembly of embodiment 1 wherein the motor module heat exchangercomprises a central heat exchanger module and lower heat exchangermodule, and wherein the lower heat exchanger module comprises a screenconfigured to trap non-ferrous particles and a magnetic trap configuredto trap ferrous particles.

9. The assembly of embodiment 1, wherein the seal section comprises athrust chamber wherein the thrust chamber comprises at least two thrustbearings and wherein each thrust bearing is fitted with a spring damper.

10. The assembly of embodiment 1, wherein the motor module comprises ahead module, power module, and base module.

11. The assembly of embodiment 10, further comprising at least two powermodules disposed between the head module and base module, wherein aflangeless connection is used to connect the two power modules to eachother.

12. The assembly of embodiment 10, wherein a flangeless connection isused to connect the head module to a power module and wherein aflangeless connection is used to connect the base module to a powermodule.

13. The assembly of embodiment 1, wherein the motor module furthercomprises a stator with a magnetic field and wherein the motor rotor isconfigured to self-align within the magnetic field of the stator.

14. The assembly of embodiment 13, further comprising an axial seatingsystem comprising a static thrust receiving face and a dynamic thrusttransferring face, wherein the dynamic face has a higher microhardnessthan the static face and the static face has a higher compressivestrength than the dynamic face.

15. The assembly of embodiment 14, wherein the dynamic thrusttransferring face has a compressive strength of at most about 4,500 Mpaand the static thrust receiving face has a compressive strength of atleast about 7,200 Mpa.

16. The electric submersible pump assembly of embodiment 1, wherein theassembly has a total dynamic head in feet to length in feet ratio ofbetween about 80 and about 300.

17. The electric submersible pump assembly of embodiment 1, wherein theassembly has a break horse power to length in feet ratio of betweenabout 4 and about 12.

18. The electric submersible pump assembly of embodiment 1, wherein theassembly is configured to produce between about 400 barrels per day andabout 4,000 barrels per day without changing the electric submersiblepump.

19. A process for producing well bore fluid comprising:

deploying an electric submersible pump within a wellbore, wherein theelectric submersible pump comprises:

-   -   a pump module comprising a pump shaft and an impeller, wherein        the pump shaft is operably connected to a motor shaft;    -   a seal section wherein the seal section is configured to        transmit torque from the motor shaft to the gas separator shaft        and absorb thrust;    -   a motor module comprising an electric motor configured to rotate        a motor shaft; and    -   a motor cooling system comprising a motor cooling impeller        configured to circulate lubricant through a motor module heat        exchanger, the motor module heat exchanger comprising a motor        module lubricant pathway, the motor module lubricant pathway        configured to increase a residence time of the lubricant in the        motor module heat exchanger,

operating the electric submersible pump; and

producing well bore fluid.

20. The process of embodiment 19, wherein the seal section comprises aseal section heat exchanger comprising a seal section lubricant pathway.

Active Cooling System Embodiments

1. An actively cooled motor assembly for driving an electric submersiblepump, the assembly comprising:

an electric motor, wherein the motor comprises an impeller, a centralheat exchanger, and a lower heat exchanger, the impeller arranged todrive lubricant into the central heat exchanger;

the central heat exchanger comprising a central exterior housing, acentral interior housing, and a central lubricant return tube, whereinthe central interior housing is disposed within the central exteriorhousing and defines a central heat exchanger lubricant pathwaytherebetween, and wherein the central lubricant return tube is disposedwithin central interior housing;

the lower heat exchanger comprising a lower exterior housing, a lowerinterior housing, and a lower lubricant return tube, wherein the lowerinterior housing is disposed within the lower exterior housing anddefines a lower heat exchanger lubricant pathway therebetween, andwherein the lower lubricant return tube is disposed within the lowerinterior housing and is in fluid communication with the lower heatexchanger lubricant pathway;

wherein the central heat exchanger is connected to the lower heatexchanger such that the central heat exchanger lubricant pathway is influid communication with the lower heat exchanger lubricant pathway andthe central lubricant return tube is in fluid communication with thelower lubricant return tube.

2. The assembly of embodiment 1, further comprising a motor housing, astator, and a rotor shaft wherein the rotor shaft is disposed within thestator and the stator is disposed within the motor housing;

the rotor shaft comprising an interior and an exterior, the interior ofthe rotor shaft in fluid communication with the central lubricant returntube and the interior of the motor housing;

the rotor shaft arranged such that lubricant may flow from the centrallubricant return tube through the interior of the rotor shaft into theinterior of the motor housing and between the motor housing and thestator.

3. The assembly of embodiment 2, wherein the stator has channels,designed to accommodate lubricant between the stator and the motorhousing.

4. The assembly of embodiment 2, further comprising an electricsubmersible pump, wherein the motor is operably connected to the pump.

5. The assembly of embodiment 1, further comprising a first central heatexchanger and a second central heat exchanger, wherein central heatexchanger lubricant pathway of the first central heat exchanger is influid communication with the central heat exchanger lubricant pathway ofthe second central heat exchanger and the central heat exchangerlubricant pathway of the second central heat exchanger is in fluidcommunication with the lower heat exchanger lubricant pathway of thelower heat exchanger.

6. The assembly of embodiment 1, further comprising a screen designed toremove non-ferrous wear products from circulating lubricant and amagnetic trap designed to remove ferrous wear products from circulatinglubricant.

7. The assembly of embodiment 4, further comprising a seal sectionlocated between the motor and the pump, the seal section comprising athrust chamber, an impeller, an interior seal housing, an exterior sealhousing, and a seal lubricant return path, wherein the interior sealhousing is disposed within the exterior seal housing and defines a seallubricant pathway therebetween, the seal lubricant pathway in fluidcommunication with the seal lubricant return path and the seal lubricantreturn path in fluid communication with the thrust chamber; the impellerconfigured to drive lubricant into the seal lubricant pathway.

8. The assembly of embodiment 6, wherein the screen and magnetic trapare located within the lower heat exchanger lubricant pathway.

9. The assembly of embodiment 6, wherein the screen and magnetic trapare located within the seal lubricant pathway.

10. The assembly of embodiment 1, wherein the central heat exchangerlubricant pathway and lower heat exchanger lubricant pathway aresubstantially helical.

11. The assembly of embodiment 7, wherein the seal lubricant pathway issubstantially helical.

12. The assembly of embodiment 7, wherein the seal lubricant pathway isin fluid communication with the central heat exchanger lubricant pathwayand lower heat exchanger lubricant pathway.

13. An actively cooled motor assembly for driving a pump, the assemblycomprising:

an electric submersible pump;

an electric motor operably connected to the pump, wherein the motorcomprises an impeller and a heat exchanger, the impeller arranged todrive lubricant into the heat exchanger; and the heat exchangercomprising an exterior housing, an interior housing, and a lubricantreturn tube, wherein the interior housing is disposed within theexterior housing and defines a heat exchanger lubricant pathwaytherebetween, and wherein the lubricant return tube is disposed withinthe interior housing and is in fluid communication with the heatexchanger lubricant pathway.

14. The assembly of embodiment 13, further comprising a motor housing, astator, and a rotor shaft wherein the rotor shaft is disposed within thestator and the stator is disposed within the motor housing;

the rotor shaft comprising an interior and an exterior, the interior ofthe rotor shaft in fluid communication with the lubricant return tubeand the interior of the motor housing;

the rotor shaft arranged such that lubricant may flow from the lubricantreturn tube through the interior of the rotor shaft into the interior ofthe motor housing and between the motor housing and the stator.

15. The assembly of embodiment 14, further comprising a seal sectionlocated between the motor and the pump, the seal section comprising athrust chamber, an impeller, an interior seal housing, an exterior sealhousing, and a seal lubricant return path, wherein the interior sealhousing is disposed within the exterior seal housing and defines a seallubricant pathway therebetween, the seal lubricant pathway in fluidcommunication with the seal lubricant return path and the seal lubricantreturn path in fluid communication with the thrust chamber; the impellerconfigured to drive lubricant into the seal lubricant pathway.

Flangeless Connection Embodiments

1. A motor for an electrical submersible pump assembly, the motorcomprising:

a head module;

a base module;

at least two power modules disposed between the head module and basemodule wherein each power module comprises an electric motor and a powermodule housing having an upper and lower portion; and wherein at leasttwo power modules are connected to each other using a flangelessconnection, the flangeless connection comprising a housing coupling, alock nut, and a spacer ring.

2. The motor of embodiment 1, wherein the upper portion of the powermodule housings comprise threads and the lower portion of the powermodule housings comprise threads which turn in the opposite direction asthe threads of the upper portion, and

-   -   wherein the housing coupling comprises an upper portion and a        lower portion, the upper portion of the housing coupling having        threads configured to connect to the lower portion of a power        module housing and the lower portion of the housing coupling        having threads configured to connect to the upper portion of a        power module housing.

3. The motor of embodiment 1, wherein the head module is connected to afirst power module using a flangeless connection and wherein the basemodule is connected to a second power module using a flangelessconnection.

4. The motor of embodiment 1, further comprising a heat exchanger.

5. The motor of embodiment 1, further comprising an impeller, a centralheat exchanger, and a lower heat exchanger, the impeller arranged todrive lubricant into the central heat exchanger;

the central heat exchanger comprising a central exterior housing, acentral interior housing, and a central lubricant return tube, whereinthe central interior housing is disposed within the central exteriorhousing and defines a central heat exchanger lubricant pathwaytherebetween, and wherein the central lubricant return tube is disposedwithin the central interior housing;

the lower heat exchanger comprising a lower exterior housing, a lowerinterior housing, and a lower lubricant return tube, wherein the lowerinterior housing is disposed within the lower exterior housing anddefines a lower heat exchanger lubricant pathway therebetween, andwherein the lower lubricant return tube is disposed within the lowerinterior housing and is in fluid communication with the lower heatexchanger lubricant pathway;

wherein the central heat exchanger is connected to the lower heatexchanger such that the central heat exchanger lubricant pathway is influid communication with the lower heat exchanger lubricant pathway andthe central lubricant return tube is in fluid communication with thelower lubricant return tube.

6. The motor of embodiment 1, wherein a power module further comprises aradial bearing sleeve affixed to a rotor and a radial bushing coupled tothe power module housing, wherein the radial bushing is configured toprovide radial support to the bearing sleeve and rotor.

7. The motor of embodiment 6, wherein the bearing sleeve comprises amaterial with a higher microhardness than material of the radialbushings.

8. A motor for an electrical submersible pump assembly, the motorcomprising:

a head module;

a power module;

a base module; and

a single-piece housing coupling comprising a first end and a second end,the first end of the single-piece housing coupling comprising threadswhich turn in a first direction, the second end of the single-piecehousing coupling comprising threads which turn in a second direction,wherein the head module is joined to the power module using asingle-piece housing coupling.

9. The assembly of embodiment 8, wherein the base module is joined tothe power module using a single-piece housing coupling.

10. The assembly of embodiment 8, further comprising a lock nut, and aspacer ring.

11. An electric submersible pump assembly, comprising:

a pump module, wherein the pump module comprises a pump shaft and animpeller;

a gas separator module wherein the gas separator comprises a gasseparator shaft and an inducer;

a seal section configured to transmit torque from the motor shaft to thegas separator shaft and absorb thrust from the pump module; and

a motor module, wherein the motor module comprises electric motorconfigured to rotate a motor shaft;

wherein the pump module is joined to the gas separator module using aflangeless connection, the gas separator is joined to the seal sectionusing a flangeless connection, and the seal section is joined to themotor module using a flangeless connection.

12. The assembly of embodiment 11, further comprising a motor coolingsystem, wherein the motor cooling system comprises a motor coolingimpeller, the motor cooling impeller configured to circulate lubricantthrough a motor module heat exchanger wherein the motor module eachexchange is joined to the motor module using a flangeless connection.

13. An electric submersible pump assembly, comprising:

a pump module, wherein the pump module comprises a pump shaft and animpeller;

a fluid intake wherein the fluid intake comprises an intake shaft;

a seal section configured to transmit torque from the motor shaft to theintake shaft and absorb thrust from the pump module; and

a motor module, wherein the motor module comprises electric motorconfigured to rotate a motor shaft;

wherein the pump module is joined to the fluid intake using a flangelessconnection, the fluid intake is joined to the seal section using aflangeless connection, and the seal section is joined to the motormodule using a flangeless connection.

Thrust Chamber Embodiments

1. A thrust chamber arranged to transfer thrust from a shaft to a thrustbearing, the thrust chamber comprising:

a shaft, wherein the shaft is operably connected to at least oneimpeller wherein the impeller generates downward thrust when inoperation;

a thrust chamber outer housing;

a first thrust runner, wherein the first thrust runner is coupled to theshaft and comprises an upward facing thrust transferring surface and adownward facing thrust transfer surface;

a first thrust bearing assembly coupled to the outer housing; whereinthe first thrust bearing assembly comprises an upward facing thrustreceiving surface and wherein the first thrust runner is configured totransfer downward thrust from the shaft to the first thrust bearingassembly;

an up-thrust bearing assembly coupled to the outer housing, wherein theup-thrust bearing assembly comprises a downward facing thrust receivingsurface and wherein the first runner is configured to transfer upwardthrust from the shaft to the up-thrust bearing assembly;

a second thrust runner, wherein the second thrust runner is coupled tothe shaft and comprises a downward facing thrust transfer surface;

a second thrust bearing assembly coupled to the outer housing, whereinthe second thrust bearing assembly comprises an upward facing thrustreceiving surface and wherein the second thrust runner is configured totransfer downward thrust from the shaft to the second thrust bearingassembly;

a first and a second damper, wherein the first damper is configured toabsorb downward thrust from the first thrust runner and transfer thedownward thrust to the first thrust bearing assembly and the seconddamper is configured to absorb downward thrust from the second thrustrunner and transfer the downward thrust to the second thrust bearingassembly; and

a thrust chamber heat exchanger, wherein the thrust chamber heatexchanger comprises a thrust chamber interior housing and thrust chamberlubricant return path, wherein the thrust chamber interior housing isdisposed within the thrust chamber outer housing and defines a thrustchamber heat exchanger lubricant pathway therebetween, and wherein thethrust chamber lubricant return path is in fluid communication with thethrust chamber lubricant pathway and is disposed within the interiorhousing.

2. The thrust chamber of embodiment 1, wherein the shaft comprises aninterior and an exterior, and wherein the interior of the shaft is influid communication with the lubricant return path.

3. The thrust chamber of embodiment 1, wherein the up-thrust bearingassembly comprises a static downward facing thrust receiving surface

4. The thrust chamber of embodiment 1, wherein the upward facing thrustreceiving surfaces of the first and second thrust bearing assemblieshave a lower microhardness than the downward facing thrust transfersurfaces of the first and second thrust runners.

5. The thrust chamber of embodiment 1, wherein the dampers areconfigured to distribute substantially even thrust load across the firstand second thrust bearing assemblies.

6. The thrust chamber of embodiment 1, wherein the dampers compriseBelleville washers.

7. The thrust chamber of embodiment 1, wherein the dampers comprisestacks of Belleville washers configured in parallel.

8. The thrust chamber of embodiment 1, wherein the thrust chamberlubricant pathway is substantially helical.

9. The thrust chamber of embodiment 1, wherein the thrust chamber heatexchanger further comprises a filter screen in fluid communication withthe thrust chamber lubricant pathway.

10. The thrust chamber of embodiment 1, wherein the thrust chamber heatexchanger further comprises a magnetic trap in fluid communication withthe thrust chamber lubricant pathway.

11. The thrust chamber of embodiment 1, wherein the outer thrust housingis threadedly connected to a seal module, and wherein the seal module isdisposed between a motor module and a pump module.

12. The thrust chamber of embodiment 11, wherein the pump modulecomprises an impeller that generates downward thrust when in operation,and wherein the downward thrust generated by the impeller iscommunicated to the thrust chamber shaft and transferred by the firstand second thrust runners to the first and second thrust bearingassemblies which are axially fixed to the thrust chamber outer housing.

13. The thrust chamber of embodiment 11, the seal module furthercomprising an interior seal housing, an exterior seal housing, and aseal lubricant return path, wherein the interior seal housing isdisposed within the exterior seal housing and defines a seal lubricantpathway therebetween, the seal lubricant pathway in fluid communicationwith the seal lubricant return path and the seal lubricant return pathin fluid communication with the thrust chamber; the impeller configuredto drive lubricant into the seal lubricant pathway.

High Speed Self Aligning Bearing Embodiments

1. A radial bearing assembly suitable for mounting on a rotatable shaft,comprising:

one or more radial bearings, each bearing comprising a bushing and asleeve, the bushing and sleeve each comprising an interior and anexterior, the interior of the bushing being in lubricated engagementwith the exterior of the sleeve, wherein the bushing is affixable to anon-rotatable bushing support and comprises a material having a highermicro-hardness than the sleeve and wherein the sleeve is configured tomount to a rotating shaft and comprises a material having a higherflexural strength than the bushing.

2. The assembly of embodiment 1, wherein the bushing interior comprisesa plurality of grooves configured to allow lubricant to flow between thebushing and the sleeve and wherein the grooves are configured todischarge debris.

3. The assembly of embodiment 1, further comprising an elastomeric banddisposed between the bushing exterior and bushing support, theelastomeric band configured to expand when in contact with lubricant andprevent substantial deleterious movement of the bushing relative to thebushing support.

4. The assembly of embodiment 3, further comprising a groove in thebushing exterior wherein the groove is configured to increase bindingbetween the bushing and the elastomeric band.

5. The assembly of embodiment 4, wherein the groove is helical andwherein the elastomeric band is configured to dampen vibration.

6. The assembly of embodiment 1, wherein the sleeve is axially movablebetween about 1 mm and about 3 mm relative to the rotating shaft.

7. The assembly of embodiment 1, wherein the sleeve comprises two outersleeves and an inner sleeve body and wherein the two outer sleeves andinner sleeve body each comprise a keyway.

8. The assembly of embodiment 7, wherein the sleeve body and therotating shaft each comprise an interior and an exterior and wherein thesleeve body comprises an opening allowing lubricant to pass from theinterior of the sleeve body to the exterior of the sleeve body andwherein the shaft comprises an opening allowing lubricant to pass fromthe interior of the shaft to the exterior of the shaft, and wherein oneor more elastomeric bands are disposed between the exterior of the shaftand the interior of the sleeve body creating a gap for the flow oflubricant from the interior of the shaft to the exterior of the sleevebody.

9. The assembly of embodiment 8, wherein the assembly further comprisesa screen configured to be in fluid communication with a lubricant, thescreen designed to filter wear products from the lubricant.

10. The assembly of embodiment 8, wherein the assembly further comprisesa magnetic trap configured to be in fluid communication with alubricant, the magnetic trap designed to remove ferrous wear productsfrom the lubricant.

11. The assembly of embodiment 1, wherein the bushing comprises abushing body and a bushing insert, wherein the bushing insert comprisesa material having a higher micro-hardness than the sleeve and whereinthe bushing body comprises a low CTE material.

12. The assembly of embodiment 2, wherein the grooves are configured todischarge debris caused by interaction of the bushing and sleeve.

13. The assembly of embodiment 2, wherein the grooves are at least about4 mm wide.

14. The assembly of embodiment 3, wherein the substantial deleteriousmovement comprises axial and rotational movement.

15. The radial bearing assembly of embodiment 1, wherein the bushing hasa microhardness of at least 500 MPa greater than the microhardness ofthe sleeve.

16. The radial bearing assembly of embodiment 1, wherein the sleeve hasa flexural strength of at least 500 MPa greater than the bushing.

17. The radial bearing assembly of embodiment 11, wherein the bushingbody comprises a material with a coefficient of thermal expansion ofless than about 5 μm/m-° C.

18. The radial bearing assembly of embodiment 1, wherein the rotatableshaft is part of an electrical submersible pump.

19. The radial bearing assembly of embodiment 1, wherein the rotatableshaft is part of an electric motor.

20. A radial bearing assembly suitable for mounting on a rotatableshaft, comprising:

one or more radial bearings, each bearing comprising a bushing and asleeve, the bushing and sleeve each comprising an interior and anexterior, the interior of the bushing being in lubricated engagementwith the exterior of the sleeve, wherein the bushing is affixable to anon-rotatable bushing support and comprises a material having a lowermicro-hardness than the sleeve and wherein the sleeve is configured tomount to a rotating shaft and comprises a material having a lowerflexural strength than the bushing.

Additional Embodiments

1. An electric submersible pump assembly, comprising:

a pump module, wherein the pump module comprises a pump shaft and animpeller, wherein the pump shaft is operably connected to a motor shaftand wherein the impeller is rotationally fixed to the pump shaft by akeyway;

a seal section, wherein the seal section is configured to transmittorque from the motor shaft and absorb thrust from the pump module;

a motor module, wherein the motor module comprises a motor configured tooperate at greater than 4,000 rpm, the motor configured to rotate amotor shaft; and

a motor cooling system, wherein the motor cooling system comprises amotor cooling impeller, the motor cooling impeller configured tocirculate lubricant through a motor module heat exchanger wherein themotor module heat exchanger comprises a motor module lubricant pathway,the motor module lubricant pathway configured to increase a residencetime of the lubricant in the motor module heat exchanger.

2. The assembly of embodiment 1, wherein the seal section comprises aseal section cooling system wherein the seal section cooling systemcomprises a seal section heat exchanger wherein the seal section heatexchanger comprises a seal section lubricant pathway, the seal sectionlubricant pathway configured to increase a residence time of thelubricant in the seal section heat exchanger.

3. The assembly of any of the preceding embodiments, further comprisingan axial seating system comprising a static thrust receiving face and adynamic thrust transferring face, wherein the dynamic face has a highermicrohardness than the static face and the static face has a highercompressive strength than the dynamic face.

4. The assembly of any of the preceding embodiments, wherein theassembly is configured to produce well bore fluid at a rate of betweenabout 400 barrels per day and about 4,000 barrels per day withoutchanging the electric submersible pump.

5. An actively cooled electric submersible pump assembly comprising:

an electric motor, wherein the motor comprises an impeller, a centralheat exchanger, and a lower heat exchanger, the impeller arranged todrive lubricant into the central heat exchanger;

the central heat exchanger comprising a central exterior housing, acentral interior housing, and a central lubricant return tube, whereinthe central interior housing is disposed within the central exteriorhousing and defines a central heat exchanger lubricant pathwaytherebetween, and wherein the central lubricant return tube is disposedwithin central interior housing;

the lower heat exchanger comprising a lower exterior housing, a lowerinterior housing, and a lower lubricant return tube, wherein the lowerinterior housing is disposed within the lower exterior housing anddefines a lower heat exchanger lubricant pathway therebetween, andwherein the lower lubricant return tube is disposed within the lowerinterior housing and is in fluid communication with the lower heatexchanger lubricant pathway;

wherein the central heat exchanger is connected to the lower heatexchanger such that the central heat exchanger lubricant pathway is influid communication with the lower heat exchanger lubricant pathway andthe central lubricant return tube is in fluid communication with thelower lubricant return tube.

6. The assembly of embodiment 5, further comprising a motor housing, astator, and a rotor shaft wherein the rotor shaft is disposed within thestator and the stator is disposed within the motor housing;

the rotor shaft comprising an interior and an exterior, the interior ofthe rotor shaft in fluid communication with the central lubricant returntube and the interior of the motor housing;

the rotor shaft arranged such that lubricant may flow from the centrallubricant return tube through the interior of the rotor shaft into theinterior of the motor housing and between the motor housing and thestator.

7. The assembly of embodiments 5 or 6, further comprising a firstcentral heat exchanger and a second central heat exchanger, whereincentral heat exchanger lubricant pathway of the first central heatexchanger is in fluid communication with the central heat exchangerlubricant pathway of the second central heat exchanger and the centralheat exchanger lubricant pathway of the second central heat exchanger isin fluid communication with the lower heat exchanger lubricant pathwayof the lower heat exchanger.

8. The assembly of embodiments 5, 6, or 7, further comprising a sealsection, the seal section comprising a thrust chamber, an impeller, aninterior seal housing, an exterior seal housing, and a seal lubricantreturn path, wherein the interior seal housing is disposed within theexterior seal housing and defines a seal lubricant pathway therebetween,the seal lubricant pathway in fluid communication with the seallubricant return path and the seal lubricant return path in fluidcommunication with the thrust chamber; the impeller configured to drivelubricant into the seal lubricant pathway.

9. The electric submersible pump assembly of embodiments 1 or 5 furthercomprising a thrust chamber arranged to transfer thrust from a shaft toa thrust bearing, the thrust chamber comprising:

a shaft, wherein the shaft is operably connected to at least oneimpeller wherein the impeller generates downward thrust when inoperation;

a thrust chamber outer housing;

a first thrust runner, wherein the first thrust runner is coupled to theshaft and comprises an upward facing thrust transferring surface and adownward facing thrust transfer surface;

a first thrust bearing assembly coupled to the outer housing; whereinthe first thrust bearing assembly comprises an upward facing thrustreceiving surface and wherein the first thrust runner is configured totransfer downward thrust from the shaft to the first thrust bearingassembly;

an up-thrust bearing assembly coupled to the outer housing, wherein theup-thrust bearing assembly comprises a downward facing thrust receivingsurface and wherein the first runner is configured to transfer upwardthrust from the shaft to the up-thrust bearing assembly;

a second thrust runner, wherein the second thrust runner is coupled tothe shaft and comprises a downward facing thrust transfer surface;

a second thrust bearing assembly coupled to the outer housing, whereinthe second thrust bearing assembly comprises an upward facing thrustreceiving surface and wherein the second thrust runner is configured totransfer downward thrust from the shaft to the second thrust bearingassembly;

a first and a second damper, wherein the first damper is configured toabsorb downward thrust from the first thrust runner and transfer thedownward thrust to the first thrust bearing assembly and the seconddamper is configured to absorb downward thrust from the second thrustrunner and transfer the downward thrust to the second thrust bearingassembly; and

a thrust chamber heat exchanger, wherein the thrust chamber heatexchanger comprises a thrust chamber interior housing and thrust chamberlubricant return path, wherein the thrust chamber interior housing isdisposed within the thrust chamber outer housing and defines a thrustchamber heat exchanger lubricant pathway therebetween, and wherein thethrust chamber lubricant return path is in fluid communication with thethrust chamber lubricant pathway and is disposed within the interiorhousing.

10. The assembly of embodiment 9, wherein the outer thrust housing isthreadedly connected to a seal section, and wherein the seal section isdisposed between a motor module and a pump module.

11. The assembly of embodiments 9 or 10, wherein the pump modulecomprises an impeller that generates downward thrust when in operation,and wherein the downward thrust generated by the impeller iscommunicated to the thrust chamber shaft and transferred by the firstand second thrust runners to the first and second thrust bearingassemblies which are axially fixed to the thrust chamber outer housing.

12. The assembly of embodiments 10 or 11, the seal section furthercomprising an interior seal housing, an exterior seal housing, and aseal lubricant return path, wherein the interior seal housing isdisposed within the exterior seal housing and defines a seal lubricantpathway therebetween, the seal lubricant pathway in fluid communicationwith the seal lubricant return path and the seal lubricant return pathin fluid communication with the thrust chamber; the impeller configuredto drive lubricant into the seal lubricant pathway.

13. The assembly of any of the preceding embodiments, further comprisinga single-piece housing coupling comprising a first end and a second end,the first end of the single-piece housing coupling comprising threadswhich turn in a first direction, the second end of the single-piecehousing coupling comprising threads which turn in a second direction.

14. The assembly of any of the preceding embodiments, further comprisinga radial bearing assembly suitable for mounting on a rotatable shaft,the radial bearing assembly comprising:

one or more radial bearings, each bearing comprising a bushing and asleeve, the bushing and sleeve each comprising an interior and anexterior, the interior of the bushing being in lubricated engagementwith the exterior of the sleeve, wherein the bushing is affixable to anon-rotatable bushing support and comprises a material having a highermicro-hardness than the sleeve and wherein the sleeve is configured tomount to a rotating shaft and comprises a material having a higherflexural strength than the bushing.

15. The assembly of embodiment 14, wherein the bushing has amicrohardness of at least 500 MPa greater than the microhardness of thesleeve.

We claim:
 1. An electric submersible pump assembly comprising: anelectric submersible pump; a permanent magnet motor configured tooperate at greater than 3000 RPM, wherein the motor is operablyconnected to the electric submersible pump; an impeller; a central heatexchanger; a lower heat exchanger; and a seal section located betweenthe motor and the pump, the seal section comprising a thrust chamber, aseal section impeller, an interior seal housing, an exterior sealhousing, and a seal lubricant return path, wherein the interior sealhousing is disposed within the exterior seal housing and defines a seallubricant pathway therebetween, the seal lubricant pathway in fluidcommunication with the seal lubricant return path and the seal lubricantreturn path in fluid communication with the thrust chamber; the sealsection impeller configured to drive the lubricant into the seallubricant pathway; wherein the central heat exchanger comprises acentral exterior housing, a central interior housing, and a centrallubricant return tube, wherein the central interior housing is disposedwithin the central exterior housing and defines a central heat exchangerlubricant pathway therebetween, and wherein the central lubricant returntube is disposed within the central interior housing; wherein the lowerheat exchanger comprises a lower exterior housing, a lower interiorhousing, and a lower lubricant return tube, wherein the lower interiorhousing is disposed within the lower exterior housing and defines alower heat exchanger lubricant pathway therebetween, and wherein thelower lubricant return tube is disposed within the lower interiorhousing and is in fluid communication with the lower heat exchangerlubricant pathway; wherein the central heat exchanger is connected tothe lower heat exchanger such that the central heat exchanger lubricantpathway is in fluid communication with the lower heat exchangerlubricant pathway and the central lubricant return tube is in fluidcommunication with the lower lubricant return tube; and wherein theimpeller is arranged to drive lubricant into the central heat exchanger.2. The electric submersible pump assembly of claim 1, furthercomprising: (1) a screen designed to remove non-ferrous wear productsfrom circulating lubricant; or (2) a magnetic trap designed to removeferrous wear products from circulating lubricant; or (3) both (1) and(2).
 3. The electric submersible pump assembly of claim 1, furthercomprising a motor housing, a stator, and a rotor shaft wherein therotor shaft is disposed within the stator and the stator is disposedwithin the motor housing; the rotor shaft comprising an interior and anexterior, the interior of the rotor shaft in fluid communication withthe central lubricant return tube and the interior of the motor housing;the rotor shaft arranged such that lubricant may flow from the centrallubricant return tube through the interior of the rotor shaft into theinterior of the motor housing and between the motor housing and thestator.
 4. The electric submersible pump assembly of claim 3, whereinthe stator has channels, designed to accommodate lubricant between thestator and the motor housing.
 5. The electric submersible pump assemblyof claim 1, further comprising a first central heat exchanger and asecond central heat exchanger, wherein central heat exchanger lubricantpathway of the first central heat exchanger is in fluid communicationwith the central heat exchanger lubricant pathway of the second centralheat exchanger and the central heat exchanger lubricant pathway of thesecond central heat exchanger is in fluid communication with the lowerheat exchanger lubricant pathway of the lower heat exchanger.
 6. Theelectric submersible pump assembly of claim 1, further comprising both ascreen designed to remove non-ferrous wear products from circulatinglubricant and a magnetic trap designed to remove ferrous wear productsfrom circulating lubricant.
 7. The electric submersible pump assembly ofclaim 6, wherein the screen and magnetic trap are located within thelower heat exchanger lubricant pathway.
 8. The electric submersible pumpassembly of claim 6, wherein the screen and magnetic trap are locatedwithin the seal lubricant pathway.
 9. The electric submersible pumpassembly of claim 1, wherein the central heat exchanger lubricantpathway and lower heat exchanger lubricant pathway are substantiallyhelical.
 10. The electric submersible pump assembly of claim 1, whereinthe seal lubricant pathway is substantially helical.
 11. The electricsubmersible pump assembly of claim 1, wherein the seal lubricant pathwayis in fluid communication with the central heat exchanger lubricantpathway and lower heat exchanger lubricant pathway.
 12. An electricsubmersible pump assembly comprising: an electric submersible pump; apermanent magnet motor configured to operate at greater than 3000 RPMoperably connected to the electric submersible pump, wherein the motorcomprises an impeller and a heat exchanger, the impeller arranged todrive lubricant into the heat exchanger; and the heat exchangercomprising an exterior housing, an interior housing, and a lubricantreturn tube, wherein the interior housing is disposed within theexterior housing and defines a heat exchanger lubricant pathwaytherebetween, and wherein the lubricant return tube is disposed withinthe interior housing and is in fluid communication with the heatexchanger lubricant pathway; and a seal section located between themotor and the pump, the seal section comprising a thrust chamber, a sealsection impeller, an interior seal housing, an exterior seal housing,and a seal lubricant return path, wherein the interior seal housing isdisposed within the exterior seal housing and defines a seal lubricantpathway therebetween, the seal lubricant pathway in fluid communicationwith the seal lubricant return path and the seal lubricant return pathin fluid communication with the thrust chamber; the impeller configuredto drive the lubricant into the seal lubricant pathway.
 13. The electricsubmersible pump assembly of claim 12, further comprising: (1) a screendesigned to remove non-ferrous wear products from circulating lubricant;or (2) a magnetic trap designed to remove ferrous wear products fromcirculating lubricant; or (3) both (1) and (2).
 14. The electricsubmersible pump assembly of claim 12, further comprising a motorhousing, a stator, and a rotor shaft wherein the rotor shaft is disposedwithin the stator and the stator is disposed within the motor housing;the rotor shaft comprising an interior and an exterior, the interior ofthe rotor shaft in fluid communication with the lubricant return tubeand the interior of the motor housing; the rotor shaft arranged suchthat lubricant may flow from the lubricant return tube through theinterior of the rotor shaft into the interior of the motor housing andbetween the motor housing and the stator.
 15. The electric submersiblepump assembly of claim 12, wherein the thrust chamber comprises a thrustbearing assembly and a thrust runner wherein the thrust bearing assemblycomprises a material with a lower microhardness than a material of thethrust runner.
 16. The electric submersible pump assembly of claim 12,wherein the thrust chamber comprises a thrust bearing assembly and athrust runner wherein the thrust bearing assembly comprises a materialwith a higher compressive strength than a material of the thrust runner.17. An electric submersible pump assembly comprising: an electricsubmersible pump; a motor operably connected to the electric submersiblepump, wherein the motor comprises an impeller and a heat exchanger, theimpeller arranged to drive lubricant into the heat exchanger; and theheat exchanger comprising an exterior housing, an interior housing, anda lubricant return tube, wherein the interior housing is disposed withinthe exterior housing and defines a heat exchanger lubricant pathwaytherebetween, and wherein the lubricant return tube is disposed withinthe interior housing and is in fluid communication with the heatexchanger lubricant pathway; and a thrust chamber comprising a thrustbearing assembly and a thrust runner wherein the thrust bearing assemblycomprises (1) a material with a higher compressive strength than amaterial of the thrust runner; or (2) a material with a lowermicrohardness than a material of the thrust runner; and a seal sectionlocated between the motor and the electric submersible pump, the sealsection comprising a thrust chamber, a seal section impeller, aninterior seal housing, an exterior seal housing, and a seal lubricantreturn path, wherein the interior seal housing is disposed within theexterior seal housing and defines a seal lubricant pathway therebetween,the seal lubricant pathway in fluid communication with the seallubricant return path and the seal lubricant return path in fluidcommunication with the thrust chamber; the impeller configured to drivethe lubricant into the seal lubricant pathway.
 18. The electricsubmersible pump assembly of claim 17, further comprising: (1) a screendesigned to remove non-ferrous wear products from circulating lubricant;or (2) a magnetic trap designed to remove ferrous wear products fromcirculating lubricant; or (3) both (1) and (2).